Page "Twin study" Paragraph 36

Modeling also allows multivariate modeling: This is invaluable in answering questions about the genetic relationship between apparently different variables: For instance do IQ and long-term memory share genes?

Do they share environmental causes?

Additional benefits include the ability to deal with interval, threshold, and continuous data, retaining full information from data with missing values, integrating the latent modeling with measured variables, be they measured environments, or, now, measured molecular genetic markers such as SNPs.

In addition, models avoid constraint problems in the crude correlation method: all parameters will lie, as they should between 0-1 ( standardized ).