David G. Horrell looks in his paper at how the Pauline literature moves away from using sibling language (άδελϕοί) and starts to refer to the Christian community as a household (οἰ̑κος θεου̑:) and wonders whether this is an indication of growing hieararchial tendencies in the early Christian church, as the household was a hierarchically structured entity.
From άδελϕοί to οἰ̑κος θεου̑: social transformation in Pauline Christianity – University of Exeter.