As the system is today, I’ve bred a +30 pedigree with a +19, both around 2/3s of my wizard level, and ended up with a +33 brim smith, which is about what I would have gotten if the second parent had no gene strength at all. It seems the +19 of the second parent contributes a very small amount or none at all, which I feel makes breeding against creatures with any gene strength a complete waste.
I propose adding the two gene strengths together, with the lower of the two being multiplied by a penalty factor before being added to the greater. The larger the difference, the greater the penalty, so a +30 and a +10 might only give +33 before any levels are considered, but it at least contributes. This would give the rare eggs found have a lot more value, and should make increasing the gene strength of the second parent before breeding it with the target creature worthwhile.