There may be a natural tendency among parents towards favouring their eldest child, new research from the University of Manchester suggests. Biologists studied a unique species of beetle that raises and cares for its young and found it instinctively favours the eldest offspring - feeding them more. "Of course human families are more complex and parent- child relationships are much more sophisticated. However, studying this beetle can help us understand the basic biological principles of how family relationships work," said research leader Dr Per Smiseth, from the faculty of life sciences. The findings were published this month in the journal Ecology .