Explain the influence of social and cognitive factors on gender development in children

The most valuable tool in separating inherited and learned behavior are twin studies. Identical twins have identical DNA so they inherit exactly the same traits. Their differences later in life are learned behaviors, not inherited.

Twin studies have been used in a number of areas including sexual orientation. The link below discusses the twin studies that have been done on homosexuality.

http://www.tim-taylor.com/papers/twin_studies/index.html