Why is unconditional love so conditional?

I can only think of a few scenarios where love is unconditional. It usually involves the love between a parent and a child. But doesn't that form of love involve require the biggest condition of all? Don't parents love their children only because they are related to them? If you don't think this is true, look at how quickly a family falls apart when it's revealed that a child isn't really related to their parent. I sometimes value conditional love more because people love me because they enjoy my company, or a quality about me instead of loving me because I share their genes. Is that wrong?