ˈtwinhoodn. = twinshipn.Apparently an isolated use.
ΘΚΠ
society > society and the community > kinship or relationship > kinsman or relation > child > relationship to parent > [noun] > condition of twin
twinship1674
twinism1796
twinhood1871
twinness1909
1871 S. WilberforceLet. in R. G. Wilberforce Life S. Wilberforce (1882) III. xiv. 387 That mystery of twin-hood which seems to reach into the spirit world.