Ok, to celebrate Father's day, let's go over an interesting note here..... There seem to be a lot of muggle dads aren't there?
No, seriously, just thinking off the top of one's head, Snape, Voldemort, Seamus. Most of the named and established "half-blood" characters where there's a muggle parent, it's the father. So why does this matter? Well I'm mostly going to focus on Snape and Voldemort here, because part of me thinks that it's the easiest way to go about it.
Looking at both, the bluntest fact is they both resent their muggle fathers, and treat them as holding them back. Voldemort killed his father, and it could probably be argued Snape may have as well*, and it's an odd comparison compared to the relationship in the other character's families. Looking at it, the pure-blood families seem to be much closer with their fathers, and the whole idea of the series, "love" is a lot more pronounced. Draco and Lucius, the Weasley children and Arthur, even Harry and James, there's a lot of affection and care that's either implied or otherwise stated in those relationships, but with the muggle parent, it's almost a mark of shame.
But why? I think the best explaination I can come up with is that much like with real life, there is a sort of class system, where to marry a muggle or a mudblood, for a wizard, may be seen as no big deal, but to marry a muggle or mudblood for a witch may be considered a step down by wizards on a whole. So as the children of that union, it's not too much of a surprise that they may not be satisfied with being the children of these "lesser" unions, and even Snape took the name of his mother over his father through school, referring to himself as the half blood prince. This was even more pronounced with Voldemort, as he essentially abandoned all family ties.
|Remember, love potions are tempting, but it's then a relationship|
based on a lie~
So, perhaps it comes from an idea, that witches that take muggle men are either stepping down, or otherwise forcing a relationship that is unnatural, and places a stigma on the child, and perhaps the family as a whole.
Though in the interest of fairness, we do have one prominant counter example in Seamus. Seamus! He described his dad's revelation that his mum was a witch as a bit of a fright, and one can only assume that his son being a wizard might have been a bit frightening as well. Though from here, we have one last possible reason why there might be a small stigma, and that comes down to culture. Looking at the Harry Potter series, one thing is clear to me, and that is that women are treated with a far more egalitarian approach than what would probably be otherwise be considered in history (perhaps due to the fact that the population is so small but that's a story for another time). So, women that come from the wizarding world, on average are probably a bit more assertive than a muggle man might be used to. Lets' combine this with what we know about western history, with men as warriors, witches and wizards were on equal footing, with brute strength being almost meaningless compared to magical ability. Thus, I will go out on a limb and say that perhaps we don't have many examples of muggle fathers, and there might be a stigma there in part because as odd as it is... the woman would have to be the "head" of the house hold, and there would likely be some emasculating effect on the father in some regard, as, while you went off running a starbucks, your wife trains dragons and your son can petrify you with a flick of your wrist. And to add ANOTHER layer of complexity, we can assume that while the wizarding community was more egalitarian, there was still a probable slight male bias due to the surrounding muggle community and what exchange of ideas and culture that came out of it. So, the effect may be ultimately that of a "stay at home dad" or even suggest the sort of class-talk that comes out of families like the malfoys, as they look down upon the poorer families, and while it may be ok generally for witches to stay at home, a working witch with a muggle husband could be considered exceptionally lower class by some as a result, because not only did she marry a muggle, she has to take care of him, their children, and trade the muggle moneys for something real like a galleon to buy some beetle eyes.
So there we have it, why that Muggle father means a lot more than you'd think, and some arm chair theorizing about wizarding culture. So why don't you share your thoughts below, or even better, read our other piece about fathers.
* See the comments for a discussion on Snape maybe killing his dad. >.> I'll post a full headcannon later, but let's just say, Snape's father was probably very unlucky.