http://www.huffingtonpost.com/2012/11/21/little-brother-blood-pressure_n_2167084.html

Having A Little Brother Linked With Slightly Increased Blood Pressure: Study

Posted: 11/21/2012

Things that can raise blood pressure: eating too much salt, stress … having a little brother?

A new study of Bolivian villagers shows a link between having a younger brother and slightly increased blood pressure levels later on in adulthood, though the Brandeis University researchers did note that the effect seemed to diminish with age.

Researchers analyzed the systolic and diastolic blood pressure levels of 374 people of Amazonian descent between the ages of 16 and 60, who came from 13 villages in Bolivia. They also took note of what the study participants’ birth order was — whether they were the oldest or youngest, had siblings, etc.

They found that the study participants who reported having a younger brother….”