These are the biggest sibling rivalries in the clothing business

• Some of the world's largest and most popular clothing brands are being superseded by their sister labels.
• Many of these smaller sister stores are able to respond to changing trends more quickly.
• Gap, Abercrombie, H&M, and American Eagle all have popular sister stores.

Sibling rivalries are the clothing business' latest trend.

Increasingly, some of the most popular apparel stores are finding themselves outpaced by the very brands they created.

This week, Racked reported that J.Crew would be bringing its successful sister brand Madewell to some of its stores. Madewell is known for its denim but prides itself on its effortless and timeless clothing that doesn't chase after fast-fashion trends. While J.Crew has struggled in recent years, Madewell has become one of the company's sweet spots.

J.Crew isn't alone. H&M, American Eagle, Abercrombie, and Gap have all increasingly found themselves being outshined by their sister labels, which are helping to boost sales at the parent company overall.

Take a look at some of these stores and their wildly popular sister brands: