I don't know if someone answered before, but here's some numbers:
If you have a pp, there are 73 other possible ways to make a pp. If you don't have a pp, there are 72 possible ways to make a pp. Since you already have 2 cards there are 1225 possible starting hands so:
AA => 5.96% chance someone else has a pair
AK => 5.88% chance someone else has a pair

EDIT: These are the odds that any one person has a pair, not that anyone does. That would vary depending on the number of people at the table

As for the KK,QQ,JJ. That's pretty improbable (1 in 10,000,000)