New mothers are often under quite a bit of pressure to breastfeed. This isn’t possible for everyone, though, and so many women end up feeling like failures due to these social pressures. Good news, then, that a new study could help to begin erasing the stigma of the bottle.

The new study, published in the Social Science & Medicine, casts doubt on previous studies that have touted the benefits of breastfeeding. Researchers looked at 665 families in which sibling children from the same family were fed differently in childhood. They found no difference among several metrics that include future obesity, hyperactivity, and academic performance.

The only category that held a significant difference between breast-fed and bottle-fed siblings was asthma. Children who were breast-fed were found to be at a higher risk for asthma later in life.

This, of course, raises the question of why previous studies have found major benefits to breastfeeding. According to the new study’s authors, these previous studies may have been pinpointing racial and socioeconomic differences among children and parents rather than any actual health benefit.

“Many previous studies suffer from selection bias,” said Cynthia Colen, lead author of the study and an assistant professor of sociology at Ohio State University. “They either do not or cannot statistically control for factors such as race, age, family income, mother’s employment – things we know that can affect both breast-feeding and health outcomes. Moms with more resources, with higher levels of education and higher levels of income, and more flexibility in their daily schedules are more likely to breast-feed their children and do so for longer periods of time.”

Colen and her colleagues have concluded that breastfeeding may not offer the long-term benefits that are generally associated with the practice. Instead, suggest researchers, income inequality, school quality, and other factors should be more of a focus that breastfeeding.

“We need to take a much more careful look at what happens past that first year of life and understand that breast-feeding might be very difficult, even untenable, for certain groups of women,” said Colen. “Rather than placing the blame at their feet, let’s be more realistic about what breast-feeding does and doesn’t do.”