This was likely more a result of the European tradition of a Platonic ideal of man, and the Christian doctrine that man ought to be virtuous. The two intertwine, and you have a Platonic ideal of a man who is both naturally and spiritually virtuous. Many scholars spent their careers showing that spiritual impurity effects natural deformity and vice versa. Not only bodily defects were understood to be errors, they were thought to be either a natural result of the person's viciousness, a deserved supernatural punishment, or a Jobian trial. Either way: ideal = good, deviant = not good.
So it makes sense that there is an ideal physical form of a man, which is definite (quantifiable) and unchanging (i.e. no evolution). I have never heard of Quetelet, but I doubt he did anything more than put a series of numbers to this preëxisting notion.
>Many scholars spent their careers showing that spiritual impurity effects natural deformity and vice versa. Not only bodily defects were understood to be errors, they were thought to be either a natural result of the person's viciousness, a deserved supernatural punishment, or a Jobian trial. //
You implicitly suggest this comes from Christian doctrine (?) which is strange as it's recorded in the New Testament (https://www.biblegateway.com/passage/?search=john+9&version=...) that Jesus was asked who had sinned in order that a blind person had become blind and he responded that no-one had, that it wasn't the result of sin.
Now, scholars who wanted to control the people's behaviour might find it beneficial to promulgate a position that sin caused deformity but it seems quite at odds with this NT account of the position of Jesus on the matter. Moreover the greater message from Jesus is to bring succour to those who are weaker, and that we are all sinners deserving of God's wrath.
I don't doubt that your suggestion matches the position of some Christians, but that does not make it a Christian position - it seems more derived from societal superstition than from Christian theology.
So it makes sense that there is an ideal physical form of a man, which is definite (quantifiable) and unchanging (i.e. no evolution). I have never heard of Quetelet, but I doubt he did anything more than put a series of numbers to this preëxisting notion.