Because typically the new chapters neophytes are trained by a contingent of marines led by a captain from their parent chapter where they got the geneseed from. That parent chapter may not even be of the first founding or the second; but because their geneseed can be traced back to the first founding its pretty much obvious who their primarch is. So sometimes the traditions and all that other stuff stick with the new chapter sometimes it doesn't. Sometimes that captain will become the new born chapters very first chapter master and sometimes he gets recalled back to his chapter. But thats how it normally goes.@Baron Spikey Well if the Astatres don't go with the High Lords as you say then why when a new chapter is formed it has similiarties to the original Legion?