Effects of Birth order on age of leaving home

Alfred Adler (1954) referred to the sibling rivalry between the first and secondborn when he said,

The striving for power in the case of a secondborn child also has its especial nuance. Secondborn children are constantly under steam, striving for superiority under pressure: the race-course attitude which determines their activity in life is very evident in their actions. The fact that there is someone ahead of him who has already gained power is a strong stimulus for the secondborn. If he is enabled to develop his powers and takes up the battle with the firstborn he will usually move forward with a great deal of elan, then while the first born, possessing power, feels himself relatively secure until the second threatens to surpass him (p. 126).