Stories of this type are complicated by logical problems such as the grandfather paradox.

By the laws of genetic relatedness, one might find a paradox here, in that Fry being his own grandfather means his father is both 50 % related to him ( since he is Fry's father ) and 62. 5 % related to him ( since Fry's father is also his son and the son of Fry's grandmother, who's by virtue of being Fry's grandmother, is 25 % related to Fry ).

The grandfather paradox is a proposed paradox of time travel first described ( in this exact form ) by the science fiction writer René Barjavel in his 1943 book Le Voyageur Imprudent ( Future Times Three ).

The paradox is described as following: the time traveller went back in time to the time when his or her grandfather had not married yet.

Despite the name, the grandfather paradox does not exclusively regard the impossibility of one's own birth.

The grandfather paradox has been used to argue that backwards time travel must be impossible.

However, a number of hypotheses have been postulated to avoid the paradox, such as the idea that the past is unchangeable, so the grandfather must have already survived the attempted killing ( as stated earlier ); or the time traveller creates-or joins-an alternate time line in which the traveller was never born.

In this theory, killing one's grandfather would result in the disappearance of oneself, history would erase all traces of the person's existence, and the death of the grandfather would be caused by another means ( say, another existing person firing the gun ); thus, the paradox would never occur from a historical viewpoint.

While stating that if time travel is possible it would be impossible to violate the grandfather paradox, it goes further to state that any action taken that itself negates the time travel event cannot occur.

Consideration of the grandfather paradox has led some to the idea that time travel is by its very nature paradoxical and therefore logically impossible, on the same order as round squares.

For example, what happens if you attempt to go back in time and kill yourself at an earlier stage in your life ( or your grandfather, which leads to the grandfather paradox )?

For example, the notion that events can be ordered into causes and effects is necessary to prevent ( or at least outline ) causality paradoxes such as the grandfather paradox, which asks what happens if a time-traveler kills his own grandfather before he ever meets the time-traveler's grandmother.

First published in 1998, it mocks the aspects of time travel such as the grandfather paradox and the Ray Bradbury short story " A Sound of Thunder ".

If CTCs exist, their existence would seem to imply at least the theoretical possibility of time travel backwards in time, raising the spectre of the grandfather paradox, although the Novikov self-consistency principle seems to show that such paradoxes could be avoided.

Upon reaching the point at which the Dahaka is supposed to kill him, the Prince uses his knowledge of the encounter to have his younger self die instead, ending the mask's power and creating a grandfather paradox as well.

Titor stated that this was the reason the grandfather paradox would not occur ; following the logic of the argument, Titor would be killing a different John Titor's grandfather in a timeline other than his own.

... The grandfather paradox is impossible.

Near-accidents cause Fry to become obsessed with protecting Enos from possible harm as the grandfather paradox means that Fry will cease to exist if Enos is killed.

His maternal grandfather joined the Army at 14 and was a mounted messenger for George Washington.

His father and grandfather followed the occupation of stone-cutters or minor statuaries ; and it is said that their family had for several ages supplied Possagno with members of that calling.

The bias of his mind was to sculpture, and the facilities afforded for the gratification of this predilection in the workshop of his grandfather were eagerly improved.

He was a descendant of Meshullam ben Jacob of Lunel, one of whose five sons was Joseph, the grandfather of Abba Mari, who, like his son Moses, the father of Abba Mari, was highly respected for both his rabbinical learning and his general erudition.

Dmitri's grandfather Ivan had been a prominent lawyer in Tsarist Russia who had displayed respect for social awareness and humanitarian principles ( including advocating the abolition of capital punishment ) that would later influence his grandson.

One source for this was when, as a very young boy, he would hear his father, grandfather, and cowboys give out loud cries when the music moved them.

It originated from the Bushells Coffee Chicory bottle that Bundaberg folks sold to his grandfather at the firm for one penny a bottle, after which they were washed and filled with the famous spirit.

In reality, it seems that Giulio was an apothecary ; as for the grandfather, he had died four years before Carlo's birth.

After the affair between David and Katrine became known, David Longfield's father ( Beatty's grandfather ), David Vandeleur Beatty ( 1815 – 1881 ), arranged for his son to be posted to India in the hope that the scandalous relationship might end.

In addition, having been close to him in their youth, she now showed excessive affection towards her uncle – whilst many historians today dismiss this as familial affection ( noting their early friendship, and his similarity to her father and grandfather ), many of Eleanor's adversaries mistook the generous displays of affection between uncle and niece for an incestuous affair.

This mutation, recombination, and the fact that the two chromosome sets ultimately come from either a grandmother or a grandfather on each parental side account for the genetic dissimilarity of siblings.

This portraiture of gladiators has been the highest interest in art for many centuries now, but it was Gaius Terentius who began the practice of having pictures made of gladiatorial shows and exhibited in public ; in honour of his grandfather who had adopted him he provided thirty pairs of Gladiators in the Forum for three consecutive days, and exhibited a picture of the matches in the Grove of Diana.

Due to a combination of ( 1 ) the traditions of dynastic succession in Aragon, which permitted maternal inheritance with no precedence for female rule ; ( 2 ) the insanity of Charles's mother, Joanna of Castile ; and ( 3 ) the insistence by his remaining grandfather, Maximilian I, that he take up his royal titles, Charles initiated his reign in Castile and Aragon, a union which evolved into Spain, in conjunction with his mother.

His maternal grandfather was General Peter Gansevoort, a hero of the Battle of Saratoga ; in his gold-laced uniform, the general sat for a portrait painted by Gilbert Stuart, which is described in Melville's 1852 novel, Pierre, for Melville wrote out of his familial as well as his nautical background.

The article " More Britons applying for Irish passports " states that 6 million Britons have either an Irish grandfather or grandmother and are thus able to apply for Irish citizenship.

When her mother returned to Ferrara, Isabella accompanied her, while the other children stayed behind with their grandfather for eight years.

He was named for his mother's maternal grandfather, Colonel John Quincy, after whom Quincy, Massachusetts, is named.

Jean-Jacques Rousseau's father Isaac was not in the city at this time, but Jean-Jacques's grandfather supported Fatio and was penalized for it.

From 1814 Keats had two bequests held in trust for him until his 21st birthday: £ 800 willed by his grandfather John Jennings ( about £ 34, 000 in today's money ) and a portion of his mother's legacy, £ 8000 ( about £ 340, 000 today ), to be equally divided between her living children.

For example, his grandfather Joseph Gödel was a famous singer of that time and for some years a member of the " Brünner Männergesangverein ".

Karađorđe's paternal ancestors left for Serbia and stopped on the way and lived in Mačitevo ( in Suva Reka ), from where grandfather Jovan moved to Viševac, while Jovan's brother Radak moved to Mramorac.

He started his reign with the intention of doing for the navy what his grandfather Wilhelm I had done for the army.

One example of these constructs found in Newfoundland is Throw grandpa down the stairs his hat, a dative construction in which the hat makes the trip, not the grandfather.

For example, a shot fired at the traveler's grandfather misses, or the gun jams or misfires, or the grandfather is injured but not killed, or the person killed turns out to be not the real grandfather — or some other event prevents the attempt from succeeding.

Levenson and Halpern, for example, note that " the narrator is sufficiently subtle ( or guileless ) to have Bathsheba's grandfather ... instigate the exaction of YHWH's pound of flesh ," as Nathan's curse in 2 Samuel 12: 11 comes to fruition.

For example, according to an entry in the Parian Marble, Simonides died in 468 / 7 BC at the age of ninety yet, in another entry, it lists a victory by his grandfather in a poetry competition in Athens in 489 / 8 BC — this grandfather must have been over a hundred years old at that time if the birth dates for Simonides are correct.

For example, a grandfather without sons was succeeded by his grandson, the son of his daughter, although the daughter still lived.

Even without DNA testing, it is possible to determine which ancestor's X chromosome was inherited by certain royalty because the gene causing hemophilia is found on the X chromosome ( for example, hemophilic Prince Waldemar inherited an X chromosome of his maternal grandmother, Princess Alice, and not that of his maternal grandfather ).

For example, in 1811, Joseph Smith, Jr .' s maternal grandfather, Solomon Mack, described a series of visions and voices from God that resulted in his conversion to Christianity at the age of seventy-six.

For example, Tsarina Praskovia, the mother of Empress Anna, came from this clan, although her branch was only distantly related to the grandfather of Sergei.

The occasional need to remove from their children's clothing dried-in bloodstains or ground-in swamp mud is generally seen by parents as more than compensated for by the broad education being received — a child's description of one of the classic battles from Ankh-Morpork's long history, for example, might be sufficiently vivid and detailed to make the parent think that the description could not have been improved upon if the child had actually seen the battle at first hand, ( which in fact he has, given the flexibility of time and space Susan has inherited from her grandfather.

One example of this is Umberto Skewes, who speaks little English but whose grandfather came to Mexico from Cornwall.

Duke Louis is reported to have been somewhat mentally unstable, a trait of nervous breakdowns presumably hereditary that showed clearly for example in his sister Joanna of Bourbon, the queen, and already in their father, Duke Peter, and in their grandfather, Louis I, Duke of Bourbon.

For example, if a son is executed for a crime leaving innocent grandsons as orphans, and the innocent grandfather has other children besides the criminal, the property of the criminal is forfeited to the crown.

For example kkapa ' cat ', jjajja ' grandfather ' and nnyabo ' madam'all begin with geminate consonants.

In 855, following the example of his grandfather Charlemagne, Charles the Bald recreated the kingdom of Aquitaine ( without Gothia ), and he gave the crown to his son Charles the Child ( Charles l ' Enfant ).

One of the most famous kings of Hungary, he distinguished himself through his policy of strengthening of the royal power following the example of his grandfather Bela III, and by the rebuilding Hungary after the catastrophe of the Mongolian invasion in 1241.