Yes, and very often to extremes.
No
Inheritance.
no
Morally and ethically yes, but not legally.
If there is no will, the law normally splits the estate between the spouse and the natural children.
If your parent dies and there is no will, there is a legal order of inheritance. The surviving spouse is next in line, then the children.
They can be sued.
If a dependent parent dies then the estate will be responsible for their tax debt. If you are over their estate then you would have to ensure that the government gets their taxes.
Normally the estate has that responsibility. If the children co-signed, they can be held personally responsible.
don't the other children have a right to the home also?
If the parent is the sole owner of any property at the time of death their estate must be probated.
They still owe the money to the estate. The executor may offset their inheritance by that amount.