There have been a number of instances where our 8 yr old grandson has shown abnormal behavior. He has always been overly interested in sexual situations. He wants to shower with his 10 yr old sister, he is constantly getting in trouble for searching inappropriate, sexual topics on his parents phones or tablets (he has been banned, but he'll sneak them when no one is looking). A few months ago he found a perfectly healthy frog, went into the house, got shoe and crushed it to death. Meanwhile his 7 yr old brother was crying. His father brushed this off as "boys will be boys" which we feel was unacceptable. He has been caught holding his cousins head under water while they were swimming together - and this was not just "horse play". He plays football and once came off the field after making a tackle, which was legal, but he was beaming with pride because he thinks he "gave the kid a concussion." He is overly affectionate with his 7 month old sister and has taken to hugging her so tightly she has vomited. His parents have told him to be more gentle, but he does it again and again. We're afraid he is going to seriously hurt her. His parents are not stringing all these isolated incidents together to see a problem, but we are. Are we over reacting or is his behavior something to be concerned about.?