Well yes and no. It might actually give a benefit to other siblings. It could manifest itself only in certain circumstances in the womb or in the environment if something helps the phenotype manifest itself...

For example there is a correlation with sibling order and homosexuality. The more boys your mother had before you the more chance you have of being homosexual. We're talking about a non-negligible increase of over 30%: https://en.wikipedia.org/wiki/Fraternal_birth_order_and_male...