the meaning of these reading (Neither and Nor)

1. What is the meaning of the sentence in bold?

How might this inability to recall early experiences be explained? The
sheer passage of time does not account for it; adults have excellent
recognition of pictures of people who attended high school with them 35
years earlier. Another seemingly plausible explanation—that infants do not
form enduring memories at this point in development—also is incorrect.
Children two and a half to three years old remember experiences that
occurred in their first year, and eleven month olds remember some events
a year later. Nor does the hypothesis that infantile amnesia reflects
repression—or holding back—of sexually charged episodes explain the
phenomenon. While such repression may occur, people cannot remember
ordinary events from the infant and toddler periods either.

2. And my second question is why Nor is used without Neither.