There's a long tradition of misunderstanding of the term congenital. Jus 'cos it's got gen in the middle don't mean it means genetic.

Congenital means present at birth - present right from the moment you left yer mothers genitals.

So an abnormality can be congenital and also be either genetic, or environmental or both.

So, lets not tie ourselves down here, a congenital defect may be a pure expression of genetic abnormality, it may be entirely the result of some infection or nutritional abnormality in the mother, or it may be something where a genetic trait will only show itself if the mother either suffers an particular infection or consumes or fails to consume something important during her pregnancy.

Genetic is about the genes and genetic characteristics can show themselves at any time and may only begin to show themselves some time after birth which would make them non con genital.