Read Hebrews 2:11 Using Other Translations
For both he that sanctifieth and they who are sanctified are all of one: for which cause he is not ashamed to call them brethren,
For he who sanctifies and those who are sanctified all have one source. That is why he is not ashamed to call them brothers,
So now Jesus and the ones he makes holy have the same Father. That is why Jesus is not ashamed to call them his brothers and sisters.