Anyone with a sibling knows that squabbles, bickering, full-on blowouts and even the occasional pinch, slap or hair pull are to be expected. These confrontations are usually eventually remedied and as siblings mature, their relationships generally improve by the time they reach adulthood.

Unfortunately, at least 16 percent of adults have hostile relationships with their siblings according to a survey from Oakland University and another 5 percent have no relationship at all, as reported in Psychology Today. And even though millions of people struggle with toxic sibling relationships, they are often quick to dismiss problems and conflict as "part of the deal." It's easy to cut family members slack, but when do disputes cross into toxic territory? Here are a few key warning signs to watch out for.

1.Your Sibling Only Calls When They Need Something

It's normal to be a little out of loop with your sibling as you're navigating early adulthood and figuring out how to live independently. Studies have actually found that sibling contact and social support decreased during early adulthood but then generally stabilized in middle adulthood. But a sibling who is only in touch for favors isn't putting in effort into the relationship. If your adult sibling never returns your calls or texts but always lets you know when they’re running low on money it may be time to make clearer boundaries. Talking to your sibling about what you need from them can be a great way to make sure your limits are respected and to build a stronger relationship.

2. You Dread Seeing Them

A lot of people only see their sibling once or twice a year because let's face it, life is busy. But if even with infrequent visits you start feeling a knot of dread about spending time with your sibling, your relationship is probably unpredictable at best and usually hurtful at worst. It may even be that your sibling is being abusive, whether physically or emotionally. "When the relationship is based in manipulation, overt or covert, you can be sure you are being used and abused. When you are living in constant anxiety never knowing or being able to predict how any engagement is going to turn out, it is time to love yourself enough to let go," psychologist Genevieve Shaw Brown explained to ABC News.

3. They're Manipulative

Even in adulthood, you and your sibling will occasionally have arguments, and you’ll each be responsible for a few of them. However, if you feel the blame is constantly thrown back to you, it’s possible that your sibling is being manipulative. They can purposely create an imbalance of power and exploit others in order to get what they want. Stopping manipulative behavior can be a little tricky but addressing it head on with confrontations, setting consequences and saying no will stop it.

4. Your Sibling Always Seems to Belittle You

It’s not enough for your sibling to have gotten straight A's all through college, land a dream job right after graduation and become a homeowner at 25, they also have to make sure that you know you’re not as accomplished. It’s not unusual for siblings to belittle each other under the guise of playful banter, since teasing is a common family dynamic, but a sibling who constantly leaves you feeling like the lesser person is probably toxic. If you’re not sure if your sibling means well and just sometimes takes it too far, consider how often you end up feeling hurt while your sibling happily watches on. A healthy sibling relationship should be fairly equal; everyone will make mistakes from time-to-time and hurt the other but it shouldn't be skewed toward one person.

5. They Are Physically or Verbally Abusive

It’s never okay for a person to abuse you in any way, but that doesn’t stop a lot of people from assuming it’s normal for sibling fights to turn violent occasionally or slam a sibling with a slew of condescending words. But if your adult sibling is hurtful, physically or verbally, it can quickly escalate into a bigger problem that can turn deadly if not addressed. According to the site Leaving Abuse, "As a rule of thumb, sibling abuse may be suspected if one child is habitually the aggressor and the other the victim. A child who is being abused may try to avoid situations where she will be alone with the abusive sibling, or display actual fear or anxiety when in his presence."

In any case of abuse, "You do what you would do in any other abusive relationship,” psychologist Peter Goldenthal told Real Simple. “Tell him you can’t spend time with him if he talks to you that way. Don’t invite him over. Don’t play victim. It’s important that you give very clear feedback.”

It’s not always easy to spot a toxic sibling and it can be even harder to address the problem once you know it’s there. However, if you think that your sibling is toxic for you, it’s important to practice self-care and enforce any boundaries you may need to keep yourself physically and emotionally safe.

ALSO: Signs You Grew Up With A Toxic Parent