The characters all grew up within one of the Su'ndi Houses and as a result the House will have impacted them from birth. Here is an attempt to explain just what that would have entailed.
The Houses on the Homeland are usually generation upon generation old. The House of your birth is not only where you were born, educated and lived but also the home of your cousins and grandfather all the way back to the original founders. In addition to this your mother will have brought you ties to another House and another bloodline which you may have had some contact with. Only Houses that are struggling or those with ties to an orphan will generally adopt new members into the House.
One of the advantages of a Su'ndi House is that it allows labour to be shared amongst the members. No matter what the wealth of the House the elderly, the infirm and the pregnant women would be responsible for the maintenance of the House and raising the children. As the wealth and size of the House increases the House may also bring in servants to perform this work and/or have members of the House take over such roles. It is likely that any child raised within a Su'ndi house spent many of their earliest days learning from the elders of the House.
When a child reaches twelve years of age they undergo a ceremony during which the House announces the path chosen for them during the next six years. As this education is expensive it is rare for a House to send its members elsewhere but not unheard of. This tendency to train youths in-House is one of the main reasons that the Su'ndi Houses have become so focused on specific family trades. Poor Houses may send the child out to work for an employer at this point, children of modest wealth may become apprentices whilst wealthy youth may be sent to one of the schools which run classes from dawn til dusk each day. It is also possible that a youth will be sent to the military for training at this point. This involves a period of schooling during which the youth will live on site followed by three years of normal military service. Any wage a youth earns during this time belongs to the House to which he belongs. A youth is also unable to make any decisions on his/her own behalf.
On the childs eighteenth birthday another adulthood ceremony is performed. At this point a youth gains a few extra freedoms and responsibilities. They begin to earn a wage of their own and gain the ability to change the path that they were set upon at twelve along with greater freedoms over their own life in general. If the Su'ndi was an apprentice before this time they will usually take on employment at the workshop where they trained and if they attended a school they will move into a more formal vocation from this point. Many, but not all, youths sent to the military academies return home at this point.
On the childs twentyfirst birthday they are considered full adults and become eligible for important positions within the House and society. The Patriarch and Matriarch hold authority even over these adults but the people that hold these roles change as internal politics shift. All that is needed to be the house patriarch/matriarch is legitimate birth, a history without serious crime and the support of at least half of the House members.
Adulthood within a House means that you work towards the success of the House rather than your own. All Su'ndi understand that they will marry to suit the needs of the House and that they will be required to produce children if necessary. Incomes are usually gathered centrally and then divided up as needs dictate and members will cooperate to ensure that food, comfort and the other priviledges of Su'ndi life are provided to all even personal property technically belongs to the House rather than the individual.
Within Kassoa and other frontier areas things tend to run a little different. In these areas it is rare for a House to be more than a generation or two old and there are relatively large numbers of immigrants that can be brought into a House. Adoption is still something that a House will approach with wariness as it is impossible to truly know an individuals background. New Houses form from year to year instead of from decade to decade and the old alliances and political structures that exist elsewhere have yet to take root. As a result frontier Houses tend to have a much greater spread of skills and professions amongst their members and as a result the children raised within them have much greater access to education.
To try and make this a little.. clearer. Which I fail at :P
Imagine a Lion Pride. Ignore the differences between males and female unless specified as only the females usually count. They give birth to cubs and then share the child raising duties between them. They hunt either alone or together but they bring the prey back home and share it. If something threatens they attack it as a group even when it is greater than any one of them alone. The adults teach the cubs to hunt wildebeast because that is what they know well enough to teach. So the young only have the one educational option - hunter. They might engage in the social part to different levels but they always come back together again before long. The boys leave to join other prides.. in the House it just happens to be the girls that leave. If one gets out of line the other members of the pride chastise them. When another male challenges (imagine a duel challenge here) the male, the strongest of them, fights on behalf of the whole group. By contrast a lone lion has to do everything themself and will often suffer as a result.