What field of study has most consistently found that the causality of same-sex sexual/affectional orientation was hand preference and fraternal birth order?

Question

Quizplus · Accepted Answer

Research in the biological field has most consistently found correlations between same-sex sexual/affectional orientation and factors such as hand preference and fraternal birth order, suggesting a biological underpinning to these aspects of human sexuality.

What Field of Study Has Most Consistently Found That the Causality