Male cat hormones

[GreenIvy]

New cat owner here, so this might be a stupid question (bear with me):

My 3 1/2 yo male cat, who is sterilized and never mated/sprayed or displayed any other behavior tied to changes in sex hormones has been behaving strange lately.
He started meowing loudly by the door to be let out (he’s indoors and has only been out on the balcony or the corridor leading to my flat). He also got into mounting his sister (also sterilized, never been in heat). He grabs the back of her neck and sort of tries to position himself behind her but I guess he has no idea how to do it or what to do afterwards.

Is it possible that he still has some urges even though he is sterilized?

 

[di and bob]

He could, even neutered cats do this, instinct is powerful. I had one male that did this to his blankets at times. It's harmles, and a natural thing to do. Your little female will most likely get tired of it and put him in his place. It's also possible that a little tissue was left behind, enough to give him some hormones. Though rare. If you want to know, the next time he has a blood test he could be tested. It sounds more to me he is restless, perhaps bored, and passing time, giving into his instincts. If it's safe, perhaps more balconey time. But if he is restless, make sure it is enclosed and cat escape proof.

 

[vince]

Yes, sterilized males will mount things, even though they're just "sport models." My Chesterfield used to try and hump my feet under the covers on the bed. I kicked him off a few times and he stopped doing that. However, once I got Meep, he kept and still keeps trying to mount her. He doesn't quite seem to know what to do, but knows he wants to do it. She'll only put up with it for a little while, then will start crying and start biting back.