About half of adult siblings of those with developmental disabilities either are or plan to be the primary caregiver for their brother or sister, but many are unprepared for the responsibility, a new survey finds.

The national poll released Wednesday indicates that among adult siblings of those with a disability, 23 percent are currently serving as primary caregivers while 1 in 3 expect to take on that role in the future. And many are finding the experience to be daunting, fraught with emotional and financial challenges and little support.

The survey conducted by the market research firm Ipsos on behalf of Easter Seals solicited feedback from 351 brothers and sisters of people with developmental disabilities from across the country. A control group of nearly 1,400 adults with typically developing siblings was also polled.

Overall, in cases where a disability was present, siblings were twice as likely to report being involved in their brother or sister’s day-to-day life, whether or not they currently served as the primary caregiver, the poll found.

For those who are the primary caregiver for their brother or sister, three-quarters said the role is a full-time job. Meanwhile, 30 percent said they don’t get emotional, physical or financial help from others.

The caregiving responsibility brings increased stress and puts strains on family life, the survey found. And, about 1 in 5 siblings said that dealing with a brother or sister with a disability has negatively impacted their relationships with other family members or their quality of life.

Despite the hurdles, however, adult siblings also said in many cases that their relationship with their brother or sister is a strong and rewarding one. More than half said that having a sibling with a disability had a positive impact on their quality of life. And, about 80 percent reported that they are close with their sibling and that the bond enhances their life, a figure that was much lower for adults with typically developing siblings.