If a child sees his father fish he may one day fish himself. If a child sees his mother sew he may one day sew himself. If a child sees a man run a marathon he may one day run himself. If a child sees a man robbed at gunpoint and killed he may become a robber himself and if a child sees two men kissing he may grow up to do that as well....Children learn what they live.
The Butterfly Effect is from chaos theory and the name relates to how a butterfly can flap its wings and cause a tornado on the other side of the world. Because the wing flap has physical effects on everything around it it can subtly influence a number of chain reactions that then lead to something happening. But this is so complex as to be unpredictable.
My proposal is that part of the influence for sexual orientation could be chaos. The human brain is not a closed system. It is very open. Sound influences the brain and probably moreso than just the sound patterns we use in everyday social communication but rather every aspect of sound and differently for different brains. And then there's smell, light, colors, gut bacteria, the person's diet, any drugs they take, and timing would also be a variable for all of these.
Studies don't show a 100% correlation with any gene or with any ordinary environmental effect so it makes sense that the butterfly effect (chaos) would influence it.
Chaos Theory is not something that would really be evident in sexuality since living organisms tend to not change in predictable patterned ways. While it would make sense that there are many variables and the more you add the greater the range Chaos Theory requires some form of linearity in order to make it work and living organisms, esp. More complex ones, just don't have it.
Generally speaking changes in humans come in two forms: "Deliberate and Slow" and "Immediate and Adaptive" (these are obviously not the official names but it's easier to understand) with neither really being something Chaos Theory would express. For instance the development of your personality could indeed play out as a Chaos Experiment but the recollection against the development wouldn't match the actual behavior in the human and obvious Chaos Theory doesn't cover extremely rapid, few variable, changes.