Stepson

A stepchild or stepkid is the offspring of one's spouse, but not one's own offspring

The traditional and strictest definition of a "stepfamily" is a married couple where one or both members of the couple have pre-existing children who live with them. More recently, the definition is often expanded to include all cohabiting couples, whether married or not. Some people also apply the term to non-custodial relationships, where "stepparent" can refer to the partner of a parent with whom the child does not live. The term is not generally used (but can be in individual cases) to refer to the relationship with an adult child who never lived in the home with the parent's new partner.

Children in a one parent family often feel threatened when their parent is dating as the parent is looking for a prospective spouse. The prospective spouse can often feel threatened as the children become part of the package within the relationship. Stepfamilies can sometimes find it difficult to feel like a family as the spouse may not feel equal to the children due to the fact that a biological parent and their biological child have a stronger bond which is separate from the marriage.

Statistics in the United States are difficult to come by, because the U.S. Census Bureau has discontinued providing estimates of marriage, divorce, and remarriage except for those that are available from the 1990 and earlier censuses.

In the United States, it is estimated that in 1987, 60 million adults and 20 million children were in stepfamilies, almost 1/3 of the U.S. population. If this trend continues, people in stepfamilies may make up half of the population by the next century. According to Pew Research Center in 2011 4 out of every ten adults have a step relative in their family with the most common being a step sibling rather than a parent.

...
Wikipedia