I should clarify that being left handed does not necessarily mean that you cannot use your right hand. Many people cannot use their opposite hand well at all, but some people have great dexterity in both hands although they favor one. Dexterity in each hand seems somewhat independent. We have not discovered what makes people one or the other, but it does seem clear that neither is a choice. I discovered I was left handed as soon as I started using my hands.
Homosexual people discover their sexuality as soon as they discover sexuality.
Homosexuality is not the opposite of heterosexuality, but instead its compliment. As most people can be dexterous with both hands but favor one, most people are attracted to both genders but favor one. Apparently men are slightly more likely to be left handed, and women are slightly more likely to be closer to bisexuality. There was a time when people in this country believed that left-handedness was a disease or a rebellious statement. Now, fortunately, we realize that being left handed is perfectly normal for those people that are, and we have been willing to elect two left-handed presidents in a row.