Scientists say that, in the future, adults will be able to pick exactly the type of child they want to give birth to.
They will be able to do this by choosing their child's genes. Genes control how a human is made.
For example, scientists claim they have found the genes that make people fat, cause mental illnesses, red hair, and even happiness.
If designer babies are possible it may only be the rich that can afford the new science.
Humans might develop into two separate species - one with superior genes and the other the 'ordinary people'.
And what happens if the science goes wrong?