Intellectually, somewhat, perhaps. Sybase was a distinct implementation. When it came on the market, Ingres IIRC was still based on QUEL. Sybase had its new T-SQL language and a novel design that made it feasible to use for OLTP. At that time, Ingres and Oracle were usually devoted to decision support, and OLTP was backed by things like VSAM.

Noted, thanks. I did think that might be the case, but I was thinking of direct parent. Anyway, good to know. Stonebraker et al?

You are actually not far off. Sybase was founded by Bob Epstein, who was Stonebraker's student at Berkeley and helped build the original INGRES system.

And Microsoft SQL Server is a descendant on Sybase since SQL Server 6, after Microsoft purchased the source code.