A study published in the journal PNAS on Monday stated a theory, according to which oldest kids act bossy and younger ones are spoiled, may not have enough evidence to prove it right. The new study was conducted by a team of German researchers.

According to an earlier research, oldest kids were ranked higher on intelligence tests as compared to the IQ level of younger siblings. The leftover data revealed weak statistical implication when it came to how birth order inclined those five procedures of personality.

In this study, the researchers found that some of theories suggested that difference in age between siblings might highlight personality differences more. A graduate student in psychology at Germany’s University of Leipzig and one of the authors of the paper, Julia Rohrer, said apart from IQ there were no strong connections between character and birth order.

One of the reasons oldest kids have higher IQ is because their parents are first-timers and they tend to give more attention to their first child and emphasize more on their education.

The study needs more research to be done, as of now the current data of so called birth-order effect has been disapproved.