Does Bi-sexuality really exist?

Apparently so, according to Time

It’s something I’ve always suspected anyway. Homosexuality is a given; it is not a choice – for two very simple reasons – no-one would choose to be Gay – and research has shown that the brains are wired differently from heteros.

Let me rephrase that: I don’t think anyone, at the youthful age during puberty, or before, would choose the difficulty associated with being different that way – or any way.

If an adult chooses to try different sexual life-styles – that is different.

But bi-sexuality means being attracted to both sexes.

Does it exist?