Androgen Androgen An androgen (from Greek "andr-", the stem of the word meaning "man") is any natural or synthetic steroid hormone which regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the embryological development of the primary male sex organs, and the development of male secondary sex characteristics at puberty. Androgens are synthesized in the testes, the ovaries, and the adrenal glands. Androgens increase in both boys and girls during puberty. The major androgen in males is testosterone. Dihydrotestosterone (DHT) and androstenedione are of equal importance in male development. DHT "in utero" causes
Fraternal birth order and male sexual orientation fraternal birth order (or the underlying variable it reflects) may be the first universal factor to be identified in development of same-sex attraction in males. Bearman and Brückner (2002) argued that studies showing a fraternal birth order effect have used nonrepresentative samples and/or indirect reports on siblings' sexual orientation. Their analysis, focusing on opposite-sex twins, did not find an association "between same-sex attraction and number of older siblings, older brothers, or older sisters". A study by Francis (2008), using the same Add Health survey but with broader analysis, saw a very weak correlation of male same-sex attraction with having multiple