It seems to me there are several different ways to categorize this:
* Completely understanding and supportive. Understands giftedness and knows what gifted child needs and provides it.
* Not understanding but supportive. Doesn't really understand giftedness but still wants to give individual child what they seem to need. Doesn't understand what the other parent is doing for the child, but doesn't actively discourage it if the child is happy.
* Non-supportive, either doesn't understand giftedness or understands and doesn't care or is actively against it. Does not support the child or other parent's support of the child and even actively works against suck support.
First situation is optimal, of course.
Second situation is perfectly fine. There are lots of families where one parent is just a great, loving, and supportive parent without really focusing on the intellectual stuff. They love the child for who they are and if the child needs advocacy or enrichment, the other parents is there for that.
This third situation is more likely to be a problem. The key it to work toward the goal of having the other parent not actively be working against what the child needs and moving toward the "accepting child for who they are, even if they don't 'get' the child."
Notice that I've put this in the context of what the child needs. Children need all kinds of things to be happy and well-adjusted, and appropriate intellectual stimulation is only one of them.
