Most parents want their children to have a happy marriage I would think.
Imo the problem occurs when some ethnic groups have cultural differences that do not fit well with other ethnic groups.
A small example:

I will make a large generalization.
In the Hispanic culture, the male is the head of the family, the dominant family member. In many cases I have noticed it is OK (even expected) for the male to cheat on his spouse, but not the other way around (probably true for Caucasians to a lesser degree imo). The women are expected to be very subservient also. I personally would not want my daughter to marry into that sort of situation. One in which she was considered a vastly unequal partner. The COLOR has nothing to do with it.

So are we talking ethnic CULTURAL differences or just purely ethnic COLOR differences?

And yes. If 50% of the parents in the US would not want their children to marry someone they felt great affection for, and had a great deal in common with, based purely on ethnic color diffences, then 50% of the US is racist by my definition.

Maybe I have a skewed view. One of my best friend's daughter has an African American boyfriend from Britian. They have a great deal in common, appear to love each other, and plan to be married. I know the boy well and he is a great kid. The girl I have known since she was a wee lass and I trust her judgement. They know if they have kids they will face problems from people that are intolerant. I wish they were the same color because of the intolerance that exists. But they are not... So they forge ahead.