Male cat nursing off his brother

Question
I recently brought home two male littermates from our local shelter.  One of the brothers likes to "nurse" on his brother.  This does not bother his brother in the slightest, fortunately, but I'm curious - is this common? Is it a security issue?

Answer
HI Jessica,

Yes this is quite common in littermates, and normally the behavior goes away. They do it for security, like sucking a thumb or a pacifier. Do be careful to check the kittens' skin daily - from time to time this nursing can become excessive and to the point that the kitten being nursed on gets sores. If that happens, you'll need to separate the kittens until the kitten with sores heals.