Public Transportation in Switzerland essentially works on a three strike principle. On the third strike, the public transport authority can make an application to start criminal proceedings against you with the police ("Strafantrag").
Art. 150 of the Swiss Penal Code says:
Erschleichen einer Leistung
Wer, ohne zu zahlen, eine Leistung erschleicht, von der er weiss, dass sie nur gegen Entgelt erbracht wird, namentlich indem er
ein öffentliches Verkehrsmittel benützt,
eine Aufführung, Ausstellung oder ähnliche Veranstaltung besucht,
eine Leistung, die eine Datenverarbeitungsanlage erbringt oder die ein Automat vermittelt, beansprucht,
wird, auf Antrag, mit Freiheitsstrafe bis zu drei Jahren oder Geldstrafe bestraft.
In short, if you use a public transport without paying for it, you will be punished by imprisonment up to three years or fine. You will likely get off with a fine unless you have any previous run-ins with the law. In addition to the fine you will be burdened with court fees (so-called "Schreibgebühren").
Art. 150 Swiss Criminal Code is a so-called "Antragsdelikt", i.e. it is only prosecuted on demand, in this case by the public transport authority, hence the reason why they have lodged a "Strafantrag".
It would be interesting to know if you immediately paid thes fines after each or your mistakes or if you gave your details and the SBB or ZVV sent the payment demands for the fines to your address?
You can try pleading ignorance of the law or extenuating circumstances, however, unless your wife was in labor or the ticket machine was broken, do not get your hopes up. One exception is if you have a month or year pass and you forgot it at home. There you have the possibility of explaining that you actually have a valid transport pass and just forgot to bring it along.