I have a girl who was normal until I saved and returned to household later. When I loaded a lot she was totally black. She is black only at daylight. At night on electric light she is greyed out.
Also she has habit to not change to naked when bathing, so I assume something may be wrong with skin. All the family has alien skin default replacement, mother and dad both from CAS, so no other skin in genetics. All other family is normal.
http://prntscr.com/uwibqp

Try resetting her. Delete her with move objects, save and exit to the hood, reload the lot.

Resetting her fixed the shadow glitch but she and her sister are still taking bath in clothes. They are spinning to change but clothes don't change. I am using PeachT alien default. How do I look if skin has child naked skin?
Both parents were downloaded without CC, so I assume their skin defaulted to this skin.

Do you use the traits mods at all? If they've got the Never Nude trait, they'll take baths in swimsuits.

I do not use traits mods.
I do use PeachT alien default and Treeag's alien skin unlocked
So far they did not made problems. Problem started with downloaded sims and their offspring skin. Both were with alien skin and no CC and I took them to the game as they were.
Now if I don't use Treeag's mod they change clothes but body skin is lost
http://prntscr.com/v1keyq
But with Treeag's mod it corrupts the game.
Can anyone help me repair genetics of sims?

The easiest fix is to use the Maxis code for whatever is borked -skin here I am guessing.

You need to change the skin code under DNA and under there is character file and in there as well.

Do you have tutorial for SimPE?

This is the best one http://www.lothere.com/verso/page/29 not sure if it mentions the character file under DNA, but you want to change both areas.