Gene Strength right now yields far too much per breeding session. Note: I have not played Ver. 0.5.0, but the change to add a cap of 200% of mage level still yields an inordinate amount of Gene Strength. At an even a modest lv 200 Mage, per-breed sessions are going to yield +400 GS.
Additionally, the second creature in the breeding doesn’t really seem to matter.
lv 1- 200: floor(Lv Parent A / 10) + floor(Lv Parent B / 10) + GS A + GS B
lv 200 - 500: the above + floor((lv Parent A - 200)/25) + floor((lv Parent B - 200)/25) + GS A + GS B
Thus a creature breeding at lv 100 with a partner lv 100 would yield +20 GS.
A creature breeding lv 400 with a partner at lv 400 would yield +36 GS.
This results in an always equal or improved new creature and allows for contributions by both parents. As your creatures scale up in level, it becomes more difficult to obtain additional GS without diminishing the “easier” to attain levels. This is to combat mainly how the game operates and awards XP. As you fight higher level creatures, you simply gain more and more XP.
Additionally, GS earned at lower levels is “worth” more proportionally in terms of statistical advantage. Going from a (0) GS creature to a (10) GS creature is pretty massive; but going from a (900) GS creature to a (910) GS creature isn’t so impacting. In the latter case, a higher level player would hold off breeding at the lower creature levels because it wouldn’t be worth it (in terms of power/ritual/resource expense). It’s also vastly easier for a higher level player to reach higher creature levels quicker.