Complex sentence: A "gay" gene does not produce homosexuality, rather, epigenetic modifications act as temporary "switches" that regulate how the genes are expressed Additionally, another study found that only 20% of identical twins are both homosexual.
Split into simpler sentences: A "gay" gene does not produce homosexuality, rather, epigenetic modifications act as temporary "switches" that regulate how the genes are expressed. Moreover, another study found that only 20% of identical twins are both homosexual.