I think it could be more about family harmony in a way that even when there are small dramas or issues, the family still manages to stay together and function as a unit. The 'nearly normal' aspect might suggest that they are not a perfect family but they have a core of harmony that holds them together through any family drama that arises.
No. A foot fetish in general is an unusual and often sexual - related fixation. When it comes to family, it is completely abnormal and unacceptable. Family relationships are based on love, respect and normal emotional bonds, not such inappropriate fetishes.