Individual people can lose education in the form of forgetting what they've learned or having no interest in applying it and thus losing practice even if they kinda sort of remember how to do something.

Generally "level of education attained" refers to what degrees have been awarded or what grade of primary and secondary school has been completed, NOT the amount of knowledge retained, nor the person's innate ability. The only way one could regress in level of education is for the degree-granting institution to revoke the degree, or for the K-12 school to set a student back a grade (while I've heard of students repeating grades, I haven't heard of students being sent down grades). While I haven't seen the film in question, it is this "level of education attained" that is usually linked to reproduction rates (as much due to the culture absorbed throughout the education process as anything else), and it is this statistic which I was arguing about.

If you wish to discuss knowledge retained, innate ability, a particular skill set, or IQ (which is a combination of all the above), instead of discussing the level of education attained, I admit to being less interested in these discussions.