Numb3rs Fanfic Finders

Hi! (again)

So, this time, I'm looking for a fic where Don and Charlie discover that they are half-brothers. I think that Margaret couldn't have children so entered a program where people with a genius mind gave their contribution to see if they could have genius children also but gave them for adoption? I'm not sure what I said is clear: to sum up, Charlie and Don have the same mother. She is some kind of genius working for the Israel's intelligence but didn't have time to raise children but she wanted to have some anyways. Alan and Margaret volonteered to be parents and that's it.
I don't remember if it was Don/Charlie or not.
Also, when they were very little, they each had to pass tests to see if they were geniuses or not.

Does it ring any bells?

Ptijade

EDIT: FOUND! See comments and big thank you to emmademaris!