Promiscuity is linked with having a history of trauma but no study to date has made a direct causal link between homosexuality (which is a pschosexual behaviour) with trauma. However, gay, bisexual men and women are more likely than straight men and women to have a history of childhood abuse. There was one study on the link to childhood maltreatment and same sex sexuality in adulthood. It cannot be determined if same sex orientation contributed to maltreatment or if it influenced sexual orientation. Furthermore, its still inconclusive.
I'm a straight female with no history of adverse childhood life experiences. I cannot impose my views on to people with a different frame of reference. However, there are plenty of people who have a history of childhood mistreatment (neglect or abuse) who do not end up gay. I think there are various factors that contribute to same sexual orientation. And its difficult to study this group without a certain degree of bias. And even if its true that maltreatment is causal it would be considered politically incorrect. Science and eugenics has also mistreated this sexual minority group.
I also have a theory that in subsistence communities (especially in isolated African communities) or in the premodern era that rates of homosexuality were close to none existent. Its endemic of societies with too much time on their hands. And if we use the Greeks as an example despite their practice of bisexual behaviour they still believed exclusive homosexual behaviour was deviant. Deviance is spatially and temporally specific.