Sex is by design of the designer, just as it takes a builder to build a building.
Which says absolutely nothing.
Nothing.
God did it.
For centuries science has said, "we don't know but we are trying to find out."
For centuries the religious ignorant has said, "god did it!"
Q: Why does it appear that the sun moves across the sky?
A: God does it.
Q: How does blood circulate through the body?
A: God does it.
Q: How is carbon formed?
A: God does it.
Your answer is ignorance. For centuries people like you have stuck your head in the sand and said "god does it".
Q: Why do some babies turn blue and die young?
A: God does it.
Science isn't so arrogant as to declare that only god knows. Science admits what it doesn't know and then sets out to find the answer and not act like a horse's a$$ declaring that god did it.
Science has:
Synthesized carbon.
Cloned living organisms.
Unlocked the mystery of DNA.
Unlocked the mystery of the atom.
Spliced genes to change the properties of species.
Developed a cure for blue baby syndrome which is a hell of a lot more than simply declaring "god does it" ever did.
What have you done but act like a jerk and judge science for having the cajones to try and find an answer?
You tell us nothing that the dunces of old didn't tell us. "God did it" is not an answer. It wasn't an answer to Galileo, it wasn't an answer to Newton, it wasn't an answer to Einstein or Bohr. Thank goodness that.
You keep sitting on your a$$ telling us that god did it like all of the other morons that preceded you and science will keep closing the gaps where you god can hide.