Katherine's father was Paon de Roet better known as Sir Gilles. He comes from Hainault in Belgium and he served Philippa of Hainault who became the wife of King Edward III of England.
Katherine's sister, also called Philippa (1346-1387) [Philippa Roet] was a prominent member of Queen Philippa's court in England. At first, she was a child companion of the children of Elizabeth of Ulster and the Queen but later on she was a lady-in-waiting. Geoffrey Chaucer became a page in the household of Elizabeth of Ulster in 1357 when he was 14 and Phillipa was 11.
Queen Philippa encouraged them to marry in September 1366. Chaucer and Philippa Roet had two sons and two daughters. The youngest son, Lewis, was born in 1381 and attended Oxford beginning in 1391. Chaucer noticed that his son was interested in science and he wrote A Treatise on the Astrolabe to explain the workings of an astrolabe that he gave him when he was about 10 years old.
A Treatise on the Astrolabe
Lyte Lowys my sone, I aperceyve wel by certeyne evydences thyn abilite to lerne sciences touching nombres and proporciouns; and as wel considre I thy besy praier in special to lerne the tretys of the Astrelabie. Than for as moche as a philosofre saith, "he wrappith him in his frend, that condescendith to the rightfulle praiers of his frend," therfore have I yeven the a suffisant Astrolabie as for oure orizonte, compowned after the latitude of Oxenforde; upon which, by mediacioun of this litel tretys, I purpose to teche the a certein nombre of conclusions aperteynyng to the same instrument.
[Little Lewis my son, I perceive well by certain evidences thine ability to learn sciences touching numbers and proportions; and as well consider I thy constant prayer in special to learn the treatise of the Astrolabe. Than for as much as a philosopher saith, "He wrappth him in his friend, that condescendth to the rightful prayers of his friend", therefore have I given thee a suffisant Astrolabe as for our horizons, compounded after the latitude of Oxford; upon which, by means of this little treatise, I purpose to teach thee a certain number of conclusions pertaining to the same instrument.
[Image credits: Wikipedia: Geoffrey Chaucer, Wikipedia: Chaucer Astrolobe]
1. Almost everyone who has European ancestors will eventually connect to European nobility so there are millions of people who descend from John of Gaunt [see Are You a Descendant of Charlemagne?]. If you know the names of all sixteen of your great-great-grandparents and their dates and places of birth, then chances are high that you can make the connection with only a little effort.