To treat scars requires cosmetic surgical techniques, which is why it is very important to treat bad acne so scars aren't made. Preventing scarring is much easier than treating once it has occurred. All bubble baths dry skin, as they contain soap. Certainly, children with problems with bubble bath should avoid them. My suggestion would be to substitute fun bath toys for bubbles, and if a child gets rashes after bubble baths to avoid bubble baths completely.
Psoriasis is a hereditary condition.
It has a definite tendency to run in families. However, not everyone who develops psoriasis has someone else in his or her family with it. A minority of children of patients with psoriasis actually develop the disease themselves. Ultraviolet light is also quite effective for psoriasis, but it carries with it, as all sun exposure does, an increased risk for later skin cancers and photoaging. Severe cases of psoriasis that don't respond to topical treatments or light therapy sometimes have to be treated with oral compounds, although one certainly tries to avoid doing so in children.