Why did the ancients bow down before their brothers?

1, since ancient times, there has been a saying that the eldest brother is the father, and kowtowing to his brother means respecting his brother.

In ancient times, people had the custom of kowtowing to their parents on festivals. As children, they all line up in order of size, kowtow to their elders, and say some blessing words on the Spring Festival or their birthdays. As the old saying goes, eldest sister-in-law is the mother and eldest brother is the father. First of all, brothers and sisters-in-law take care of and cultivate their younger brothers and sisters like parents, and younger brothers and sisters respect them like parents.