People seem to have little difficulty in accepting the modifiability of “environmental” effects on human development. If a child has had bad teaching in mathematics, it is accepted that the resulting deficiency can be remedied by extra good teaching the following year. But any suggestion that the child’s mathematical deficiency might have a genetic origin is likely to be greeted with something approaching despair: if it is in the genes “it is written”, it is “determined” and nothing can be done about it; you might as well give up attempting to teach the child mathematics. This is pernicious rubbish on an almost astrological scale. Genetic causes and environmental causes are in principal no different from each other. Some influences of both type may be hard to reverse; others may be easy to reverse. Some may be usually hard to reverse but easy if the right agent is applied. The important point here is that there is no general reason for expecting genetic influences to be any more irrevocable than environmental ones.
I think that, in mathematics education, it is the environmental damage that is harder to reverse. Millions of innumerate people are innumerate not because of the genetic defects, but because they were (perhaps irreversibly) damaged at earlier stages of their education.