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Can you marry your foster brother?

This is a complicated question that does not have a simple yes or no answer. There are many factors to consider when determining if you can legally marry your foster brother. In this article, we will explore the laws and regulations around foster relationships, marriage laws, and the ethical considerations of marrying someone you view as a sibling.

Foster Relationships

First, let’s look at how the law defines foster relationships. When a child is placed in foster care, the foster parents take on the legal responsibility to care for the child. However, they do not have the same legal rights as an adoptive parent. The biological parents still retain many parental rights even though the child is not in their custody.

Foster children may live with one family for many years or move between several different homes during their time in the system. Regardless of the length or closeness of the relationship, foster parents are considered temporary caregivers in the eyes of the law.

There are a few types of foster care arrangements:

  • Traditional foster care – Child lives with a non-relative foster family
  • Kinship care – Child lives with relatives or close family friends
  • Therapeutic foster care – Child with significant emotional/behavioral issues needs specialized care

No matter what type of arrangement, the foster family essentially has a contract with the state to provide care for the child. However, they do not legally become the child’s parents. The foster child retains ties to their biological family.

Foster Sibling Relationships

Children who are placed into the same foster home become foster siblings or foster brothers/sisters. They may form strong emotional bonds by living as a family unit. However, they are not legally considered family under the law.

Foster siblings do not have the same restrictions placed on them as biological or adoptive siblings. For example, many states prohibit marriage between siblings who are blood-related or adopted. But foster siblings are not bound by incest laws because they are not legally family.

Marriage Laws

Marriage laws are determined at the state level in the U.S. This means the rules around who can legally marry vary between different states.

Age Requirements

All states have minimum age requirements to get married. Most states set the marriageable age at 18 but several allow younger minors to marry under certain conditions, like consent from a parent or judge. Some key age requirements by state:

State Minimum Age
Massachusetts 18
Alaska 16
California 18
Mississippi 15

Prohibited Marriages

Most states have laws prohibiting marriage between close relatives. This is to avoid the genetic risks associated with incest. Prohibited marriages may include:

  • Parent and child
  • Brother and sister (including half-siblings)
  • Uncle/Aunt and niece/nephew
  • First cousins

However, foster siblings are not included in these prohibited relationships. Since they are not legally family, states do not restrict marriage between foster brothers and sisters.

Same-Sex Marriage

Same-sex marriage was federally legalized in the U.S. in 2015. All states must now recognize marriages between two people of the same gender. Therefore, marriage between same-sex foster siblings would be subject to the same laws and restrictions as heterosexual couples.

Ethical Considerations

Even if it is legally permitted in your state, there are some important ethical issues to consider with marrying a foster sibling:

Power Imbalance

There may be an inherent power imbalance if you seek a relationship with someone who was recently under your parents’ guardianship. The foster sibling may feel pressured to follow your wishes rather than make decisions freely for themselves.


Some foster sibling relationships have unfortunately been the result of grooming from a young age. This type of predatory behavior should be reported to authorities immediately.

Emotional Issues

Viewing someone as a sibling then shifting to a romantic relationship can be emotionally damaging. Even if not legally prohibited, these types of relationships may cause long-term psychological harm.

Family Conflict

Pursuing romantic involvement with a foster sibling may cause serious conflict within your family. Other siblings or parents may have concerns about the ethics of the relationship. This can permanently damage family bonds.


The legality of marrying your foster brother or sister depends on the laws in your state. In most states, it is not prohibited like sibling incest. However, just because something is legally permitted does not mean it is a good idea or morally right.

A relationship with a foster sibling comes with a unique set of challenges and ethical dilemmas. The decision to pursue romance or marriage should not be taken lightly. At a minimum, both individuals should seek counseling to address any underlying trauma or co-dependence. With thoughtfulness and care, foster siblings can build healthy relationships, whether platonic or romantic.