Should I throw only Same Sex Birthday parties for my children?

Hello my lovelies, you already know my shares come from experience or observation.
While on my grandma duties a few days ago one of her old home attendants came to pay her a visit which she loved.
As they chatted it up I went about my biz, folding laundry, sorting mail etc. something made me stop and eaves drop on the conversation, something the home attend said.
Back ground she is very very "old school", meaning no sex before marriage, one boyfriend and marriage type. So she commented that her son was turning fifteen and she was going to have a house party for him with a few friends. No problem right, wrong she said no girls could come because you know what could happen.

At which point Mari (me lol) walks out the room and says "oh but doesn't he go to school with girls?"
Of course the answer was yes but her rational was anything can happen in an apartment. Geez I couldn't walk away fast enough because of course my almost ninety-two year old grandma agreed. I felt like I was trapped in the stone age. It made me recall an old post I wrote which I am including here.
Tell me what you think.

Repost:

When I encounter something that I have never experienced I try and am trying to stay open and look at all perspectives.  Parenting is a tricky journey and some of the things that I have come across in my 18 years on this road have caused me to pause or just plain laugh out loud. I realize that age and upbringing have a lot to do with the way some of us choose to parent. This being said, I have a story to share.

I was invited to a friend of a friend daughter’s 11th birthday party a few days ago. It was held at one of those Fun zone type places. Everything was set up beautifully and we had a great time. So what is the problem right? Well the “problem” I found was that her whole class was invited, minus the boys.
The following day when I spoke with my friend I asked “Why were there no boys at yesterday’s party?” She replied that the parents didn't feel comfortable with the boys around.
Really? Don’t the boys already go to school with them? Don’t they spend at least 8 hours together a day? Don’t they have lunch and recess together?

I found the split to be silly. I saw no reason for it. We don’t live in a single sex society. We engage daily with the opposite sex. At 11 years old our children should know what proper behavior is. We as parents need to teach and reinforce, then see how things go. Not use separation as a means to “try” and solve a problem that may not even exist. I was confused as to what year this was. I mean my mom was a bit of a pain when it came to boys but even she was “Modern” to some degree for her time.

Do you think that child felt sad some of her classmates could not attend? Do you think she will have many friends if her parents continue to split her parties up or any other activities? Do you think she felt embarrassed?
Was there a reason to feel uneasy in the first place?

Ok so two stories almost two years apart, same idea do these parents have valid reason for such extreme or is that totally outdated? Is there a better way to handle this and what would they be?
Start a conversation.

Always stress free xo.