The behavior is, but some people are apparently more likely to develop same gender attraction than others.
As biological entities, there is s light chance of genetic anomaly, like that which produces too much estrogen or too little testosterone in a male. But that is extremely rare in the general population. Homosexuality is a learned behavior.
A huge clue is the incessant effort by sexual degenerates to teach children to be like them. If that does not send warning signs then remaining naive is a choice also made, to enable the continued rise in degeneracy so as to avoid the issues, to the detriment of society..