It probably is because they are coming from free-range peafowl. Free-range peafowl probably do have good genetics since the strongest survive and in a penned setting usually even the runts survive and get to breed.
Yes yearling peafowl usually look like the above photo that Birdrain92 posted.
Also, the peahen looks to be an India Blue but 2 of the peacocks are blackshoulders and one looks like it might be split to blackshoulder.![]()
I think they are all from the same hen (unless another hen was sneaking eggs into the mother's nest) and one that died was definitely a BS hen

So, I think both hens may be split for BS. The one in the pic has some white on her breast, the other is classic IB colors. All the cocks look very similar, we can only tell them apart by the slightly varying amounts of white on their wings.
Which cock do you think is only split for BS? I thought BS was a lack of barring. The cocks all have white markings on their wings, is that typical for BS?
I can do better with pics sometime, I was intending to take turkey pics, but the peas looked so good I snapped a few of them too, but from outside the run.