Yep. Evolution is really just a description of the consequences of differential reproduction. Rare behaviors (adoption) that are not optimal but which are driven by drives (better motherhood) that may have big evolutionary upsides may simply not be selected against very effectively, and evolution is always limited by the pool of mutations and what is possible for the organism at that point. If there is no mutation that both eliminates adoption and preserves the beneficial effects of the drive, it may not happen...