You have asked an interesting question. There are different answers depending on the context in which the question is asked.
The scientific and legal meaning of descendant is all the persons who have descended from a common ancestor. In this context, a step-child would not be considered to be a descendant.
However, for purposes of inheritance, a legally adopted child and their issue are considered descendants. A step-child in a blended family who has not been legally adopted is not considered an heir at law.
To a genealogist who is researching a family line, an adopted child would be noted as adopted and not a descendant of the blood. Similarly, to a medical researcher who is examining a troublesome medical history, an adopted child in the family line would not be considered a descendant.
A step-grandchild is not considered a legal descendant of their step-grandparent, as there is no biological or legal lineage between them. However, in a familial or social context, many may view step-grandchildren as part of the family and include them in family gatherings and relationships. The definition can vary based on individual family dynamics and cultural perspectives.
You are considered the legal descendant, for purposes of inheritance, of the parent who is listed on your birth certificate. However, someone supplied false information at the time of the recording of the birth and that issue may come up in the future. A court order could change the situation but until that time the birth certificate would control.
No, there must be a blood relationship.
Lineal descent is metaphorically in a straight line; a lineal descendant is the child of the child of the child (repeat as necessary) of your own child. It is not the child of your sister, and so forth.
Yes. That is also what makes it legal for the step-parent to carry the step-child on their health insurance.
Not unless his mother is married to the man they are living with
Yes, that child would be considered your half-brother or half-sister, not a step-sibling. A step-sibling is typically defined as the child of a stepparent, where there is no biological relation. Since you share one biological parent with that child, they are classified as a half-sibling.
Yes.
A male parent is considered to be the father of the child in most cases. A male parent can also be a step-father or even the grandfather of the child.
yes he did, i am a descendant
yes
Maybe, but not normally. Unless the step-child was adopted they are not a descendant of the deceased. However, if their parent received the estate through their spouse, they may have a claim. You need to consult a probate attorney in your jurisdiction with all of the specifics.