I don’t have a degree in genetics, but I do find it fascinating, so I thought I would throw out some other possibilities. 

Red heads that have a child together will always get red headed children.  The color may vary from strawberry-blond to deep red, but it will be red.  If it’s not, the guy would do well to have a dna analysis done.

Going off of the previous model of Aa to Aa, the chance of a red head babe is 25%.

However if we change that to Aa to aa, the chance of red in children is 50%.

If a red head (aa) has children with someone of AA, then none of their children will have red hair, but all of the kids will carry the gene and there is a good chance they could have red head kids themselves.

Keep in mind, each child has the same chance as the next kid.  An aa that has kids with an Aa may not bear any children with red hair, or they may all have it.

As for the original question:  Because you are red and the guy’s mother is red, the chances of conceiving a red are 50% per child.

As for myself, I have red hair and three kids with my husband.  He has very dark hair, neither of his parents was red, but he has a red haired aunt and his beard has some red.  Before we were married and had kids, I was fairly certain that he was Aa.  After our first son was born with flaming orange hair, I can guarantee it!