I am taller than the average American male. This can only be for a combination of two reasons: genes and the environment. I have no idea which environmental factors might have made me taller than average, so if my height advantage is part genetic and part environmental in origin I will probably only pass on the genetic portion to my children. Unless they, by sheer luck, also get the same environmental advantages I did, they will be more like the average person, in terms of height, than I am, but still somewhat taller than average due to my genes. They will have regressed towards the population mean.