After a bit of testing, I have come to this conclusion.
There appears to be a bug where both Motor and Mental child skills proceed into Video Gaming, resulting in the Video Gaming skill to be reset when both child skills are levelled up to 10. Example:
Motor Level 10, Mental Level 6, Video Gaming Level 7
becomes
Motor Level 10, Mental Level 10, Video Gaming Level 1
The result is the Video Gaming skill to drop without a cheat. Anyone else able to confirm this?