What we are, in large part, depends on our genes. It is the hand we are dealt when we are born, and the cards we play our entire lives. You can study as hard you can, but some people will be smarter. Work out as much as you want. Some people are born to be bigger, or prettier, or more artistic.
The hand you get depends upon the luck of the draw. Which genes you get from your mother, which you get from your father, and how they combine to make you a unique individual, is largely a matter of chance. In the game of life, the shuffling of genes to create a new individual is called sex.
But life does not have to be this way. We humans believe we are more than that: as much what we think, what we believe, what we imagine and what we hope as what we are physically. And that can transcend the selfishness of our genes, the fight for fertility, and the siren song of sex.