35 LBS for a 4 month old siberian is on definitely on the big side but not horribly uncommon..ther e are so many backyard breeders selling 75-90 LBS siberian huskies now a days its hard to know. Typically, a male siberian should not weigh more then roughly 60 LBS full grown, which would make your boy just a bit oversized. On the other hand, I think 4 month old mals are about 45-50 LBS, or more. Our foster mal was about 62 LBS at 5 months. Do you have any other pictures of him from the sides/rear/paws?
His head looks more sibe to me then mal. Hows his tail? a Mal's tail should "snap" more then a sibes.
He's friggin adorable whatever he is!