Can Step Siblings Get Married? (Legally And How Common Is it)

There seems to be several gray areas in the world of marriage and relationships. The legalities around incest (marrying or having relations with a sibling or cousin) vary from state to state, so some people might assume that the same rules apply to step siblings. 

However, the general rule of marriage is that if you have no blood relations to the person you wish to marry, there is nothing stopping you from marrying them. This means that, yes, step siblings can get married! 

Of course, there are factors that need to be considered such as ethics, religion, and subsequent family feuds during the potential future divorce. 

If you’re wanting to seal the deal with your step sibling, or perhaps you are merely curious about the legalities of marrying a step sibling, here is our ultimate guide! 

Can step siblings marry legally? 

There are currently no laws against marrying a step sibling in the whole of the United States, meaning step siblings can legally marry. This is because while you might be related to your step sibling through marriage, you are not related by blood. This means that the act of marrying a step sibling does not constitute as incest. 

Consanguinity laws 

Consanguinity (meaning “blood relations” in Latin) is the name of the laws surrounding kinship to another person whom you are related to by blood. In most cases, consanguinity laws make it illegal to marry any of the following: 

  • Biological siblings
  • Biological half-siblings
  • Nieces and nephews
  • Aunts and uncles
  • First cousins (in some states)

The consanguinity laws around marrying a first cousin differ from state to state, however second cousins can legally marry in every state. This is because they aren’t related by blood. 

The reason why consanguinity laws are in place is that incest can cause harm to family relationships. In most cases, incest can be charged as statutory rape, abuse, coercion, and child molestation. 

Despite the consanguinity laws, people will still secretly and illegally marry their biological sibling/half-sibling/niece/nephew/aunt/uncle in the United States. 

How common is it to marry a step sibling? 

The act of marrying a step sibling is a taboo topic. Sure, you aren’t related by blood, but you still share the same parents by nurture. At the end of the day, there technically isn’t anything legally or biologically wrong about marrying a step sibling. 


As the act of marrying a step sibling is such a taboo topic, there is little data or evidence to prove how common it is.

It is suggested that a lot of couples built up of step siblings only stay in relationships (sexual relations and dating) without getting married due to the potential complications surrounding divorce – either of the couple or their shared parents. 

It can be assumed that because there are currently no laws against marrying a step sibling, the act of marrying a step sibling is probably as common as marrying a second cousin. It’s taboo, which is why figures and data about marrying a step sibling aren’t documented as much as same-sex marriage or marrying someone of a different religion. 

Can step siblings get married in Islam?

As with any forms of marriage, different religions will have varying rules and general opinions around marrying a step sibling. 

According to Islam, however, the rules are fairly simple. If the step siblings have not shared the milk from the breast of the same mother, then they can get married. If they have been breastfed by the same mother, then they cannot get married. 

Is it OK to marry a step sibling?

So, we have established that step siblings can legally marry. Whether it is OK to marry a step sibling is another argument in itself. 

At the end of the day, the heart wants what it wants. Love and relationships shouldn’t be anyone’s business. If you and your partner are prepared to commit to a lifelong marriage, despite all the taboos, then it is OK to marry them. 

However, marrying a step sibling isn’t as simple as marrying your best friend. Like a regular marriage between two non-related folk (not by blood or marriage), there are two families that will unite. Unlike a regular marriage, these two families have already been united by marriage, which is where it gets complicated. 

If you are thinking about marrying your step sibling, you will have to discuss it with both families. It’s a tough decision and topic, but complete transparency and consideration is needed to prevent any potential risks. 

For example, there is always the risk of divorce. This could be divorce between the married couple, which makes things very awkward for their parents. This could also be divorce between the parents of the married step siblings, which makes things very awkward for the new couple. 

Unfortunately, if you’re thinking about marrying (or even dating) a step sibling, you will have to accept that both families (and a lot of other people) will be handing out opinions left right and center – whether it’s solicited or not.

Sure, some families might be cool with it, but this marriage won’t be as simple as a regular marriage between two people who aren’t related by marriage. 

You’ve also got to consider how long you have been step siblings for. Have you been related by marriage for 3 years, or 13 years? Are you sure you’re in love, or are you being coerced? If you feel as if you are in an unhealthy relationship, it is imperative that you seek proper help.

It can be awkward, as you might not want to burden your parents with the stress of problems between their kids, but if you are to treat your relationship as if you are not step siblings, then it’s got to be a healthy one free from abuse. 

So…can step siblings get married?

To conclude, yes – step siblings can get married. As step siblings aren’t related by blood, nor have they shared the same milk from the same mother (in Islam), then there are no laws to prevent step siblings from marrying one another.