Sexy Primes

Just came across a interesting article on Wikipedia. It's about sexy primes.
What the heck, I hear you say. You mean, we have numbers that are more aesthetically superior to other numbers? That thought seems weird at first glance, but NO! Of course not. Sexy primes are actually pair of primes that differ by 6. So, if we consider the prime numbers 11 and 17, they are sexy primes, because both 11 and 17 are prime, and they differ by 6 (17 - 11 = 6) .

But why 6, now I hear some say. Why not 4, or 8, I hear people argue. The reason the difference between the primes is 6 comes from their names, sexy primes. The term "sexy primes" originates from the latin word for 6: sex.

If you are a mathematician, how would you define sexy primes?