It's good she shows no symptoms but even the worst genetic disorders often don't show in all family members, even when they're inbred. So I wouldn't discount it entirely. But if you're not planning to breed him, no worries about it. I'd bet that even if it was genetic, you could inbreed him with his own offspring, and his own grandchildren, and still get some normal birds.
As for the pecking being possibly not as bad just based on the genders involved, there are no gender differences there when you're talking about actual attacks as opposed to pecking order reinforcement. Hens aren't known for being gentler in that way.
Some of us do look at things like this in humans. Some don't. I am one of those who does, but health is one of those things which frightens most people, so it's just better not discussed unless talking about animals strictly in the majority of cases, lol.
The vast majority of health issues and the treatments for them that we discuss with chickens and other animals apply directly, or almost identically, to humans as well. There are more similarities than differences, generally speaking.
A little while back a teenager was posting on this site about a rooster of his, and mentioned he was unable to recall what he'd done for the same problem last year, just as a passing mention, but the way he said it reminded me of some similar circumstances with a family member, so I mentioned this and recommended he consider the memory loss something to address, not leave be. (Memory loss like his tends to progress unless the cause is addressed and it's often quite easily fixed especially in young and otherwise healthy people). I mentioned a few harmless herbs proven to improve memory and suggested he get himself checked out by a GP.
Others in that thread immediately condemned my suggestions and told me off because apparently young people simply do not suffer from health issues (LOL) and shouldn't even suffer the suggestion of the possibility. What sort of irresponsible fear-mongerer was I, someone asked.
Anyway, long story short, the kid PM'd me and we discussed it, and he did indeed have something seriously wrong with him, and even before he mentioned his inability to recall events a year past, he had been having MRIs etc because his doctors knew something was badly wrong but couldn't find out what exactly. His memory loss and migraines were so bad that he was actually expecting to die soon, and this was even before I ever replied to his thread.
The censure I received from a few other forum members for suggesting he address the memory issues, and not consider them normal for his age, is a good example of the general response when trying to find the causes behind health faults in people. Hence my reason for rarely discussing that sort of thing. (Some memory loss is normal enough for people to experience at different stages, for different reasons, but the specifics of his case were red flags, you will never hear of those specifics without it being indicative of something seriously wrong, so I spoke up about it, otherwise I would have remained silent on it like usual concerning human health).
The chasing is a little weird but it doesn't necessarily mean he's aggressive. It is standard behavior for an insecure rooster. A secure male has females willing to mate with him and is calm around them; he has no need to chase. His insecurity could be because he's been attacked, or because he has some underlying weakness he's aware of, or because he's not got the full complement of instincts. Or it could just be because he's still young.
Hens who were raised without roosters can be difficult companions for roosters, too, and the mating interactions can be constantly stressful and discordant in such situations; this is one form of 'normal' you see in many farmyards which is actually somewhat stressful for both parties, but many people think it's just the natural state of things. It's not. In the wild you don't see that sort of freakout every time they mate; this is a byproduct of human intervention. The issue there is probably the breed of hens having been reared without males for generations, having lost the instincts regarding a male's social role, and retaining only the vaguest mating instincts (enough to enable mating but not necessarily any positive perceptions of it). So, as you've probably noticed, they squat and move their rump feathers out of the way to mate, cooperate physically, but complain bitterly the whole time. A hen who doesn't want to mate will simply not move her feathers out of the way and get into position, and the rooster cannot force it, despite appearances; he doesn't have a penis and if she doesn't get into position, all he can do is sit on her back fruitlessly. Many people think they're seeing something like rape because of the complaining so many hens do, but it's just semi-instinctive birds making a hash of what is simple for birds with clearer instincts. Soundly instinctive birds don't have these problems.
A breakdown of natural communication, caused by people breaking down their natural social units and raising them in isolation from the natural family structure, results in weak or defective instincts over generations and higher chances of aggression and abnormal behavior, as well as neuroses. If a bird's most recent ancestors were always separated by gender, and only ever brought together for very brief periods to mate, and then separated again, then over a short time the calmer, friendlier social instincts are replaced by frenzied, frustrated, often highly aggressive mating behaviors. Anyone who doubts the possibility of that simple instinct modification can experiment with their own birds, it breeds in and out fairly quickly.
Some hens never do more than tolerate mating. Hens with good instincts are active participants and will only refuse sub-par or genetically badly matched roosters, or complain if he's clumsy or rough, not complain every time and run away as a rule, and scream blue murder during mating.
A rooster with good instincts will understand how to woo hens and unless something's seriously wrong with him and/or the hens, he won't have to chase them, they will come to him. Many people think animals have infallible instincts but we've altered many of them, even entirely bred some of them out of some individuals and families and breeds.
Aaaaaaanyway.... Best wishes with your flock.
