# Regression towards mediocrity by Galton

We have learned that the term regression which doesn't resemble anything of what it statistically does was coined by Galton in his study about the relationship of heights of father and the son. But I had never understood what his study illustrates the "regression" toward the mean because every textbook as well as the original study state that a tall father has a tall son (and vice versa), and this doesn't imply anything about regression toward the mean. In order to make that sense, a tall father should have a shorter son. But I realized that it might just mean that the slope of the regression line is less than one implying the positive deviation from the mean height for the father's height corresponds to the positive deviation from the mean for the son's but not as much as father's. Every time the son has another son, the eventual son will have the mean height. Is this what Galton meant?