Could the fact that America has been a melting pot of immigrants moving in from various parts of the world affected the average American height? I am from South

Could the fact that America has been a melting pot of immigrants moving in from various parts of the world affected the average American height? I am from Southeast Asia, where average heights are less than European or Americans'. And my impression is more people like me have settled in America in recent years than say several decades ago, causing the average American height to go down. In which case, nutrition and healthcare may not be the (sole) cause.