A debate which has divided the union for nigh on three decades was swiftly and definitively ended on television last night, when a viewer calling in to Bravo's "Watch What Happens Live" asked guest Elizabeth Olsen (sister of the famous twins): "Who do you like better: Mary-Kate or Ashley?"

The better Olsen is: Ashley.

Because Mary-Kate forgot her sister's birthday. (Not her twin sister. The other less important sister that she doesn't love as much.)

"Ashley remembered my birthday," responded the actress, "but I don't hold grudges against Mary-Kate forgetting mine. She was out of town!"

[There was a video here]

Elizabeth, who turned 25 on Sunday (NOT THAT MARY-KATE WOULD KNOW) went on to explain that her less thoughtful sister is currently on vacation in Jamaica...

...and also literally capable of murder:

"Mary-Kate is literally going to come home from her vacation and shoot me that I said that."

As any magazine profile of the Olsens will tell you, the Olsen twins are very different despite the fact that they don't look very different. Ashley, right handed, is the neater, Type-A twin, whereas Mary-Kate probably wouldn't have forgotten her little sister's birthday if she hadn't been so busy making love to an old Frenchman beneath the sultry Jamaican sun. And she's left-handed.

In a scrambling attempt to save her own life, Elizabeth added that the sisters are "all very close!"

What a shame that her most recent birthday will be her last.

[Art by Jim Cooke, Source Photo via Getty]