Let us imagine that John has a son Peter, a grand-daughter Sarah, a great-granddaughter Ulla and a sister Dora.Dora has a child Kim, a grandchild Robert and a great-grand-daughter Tabitha.
Because you have one parent in common, you are partly (half) related "by blood".
IN-LAWS: If your brother or sister gets married, his/her new spouse becomes your sister-in-law or brother-in-law, but the family of your new sister(brother)-in-law does not become related to you, only in-laws to your newly married sibling.
When you marry, however, you do acquire a whole family of in-laws of your own.
Your new mates family now become your father-in-law, mother-in-law, sister- or brother-in-law.
But your nieces nephews and those of your spouse are and so on down through the generations. To understand "removed", it is important to keep the generations in order.
But what is the relationship of your child to your great-grandniece? A simple diagram is an excellent method of doing this.a first cousin to Peter but each generation is one "remove". Robert is a second cousin to Sarah so he is a second cousin once removed to Ulla.Thus for Peter, Robert is a first cousin one generation removed, a term usually shortened to "once removed", and Tabitha is then Peters first cousin twice removed. Once while working on our family genealogy, I visited an eighth cousin once removed!When his first wife died, he remarried and had another son.His second wife also insisted on naming her son Japhet after his father. It must have been most confusing ---a father with two sons, Japhet #1 and Japhet #2 GENEALOGY versus FAMILY HISTORY: Although currently the two terms are frequently used interchangeably, there is a difference between a genealogy and a family history.In-laws, like step-relatives, are not related "by blood" but by "extended family ties".