If anyone doubts the extremes to which some conlang enthusiasts will go, consider the sad case of four children raised speaking Klingon.
4 CHILDREN TAKEN INTO CUSTODYNo word on whether they were home-schooled. I suppose they must have understood English if only to watch the show, unless their father provided simultaneous interpretation.
Report of father's speaking in Klingon, a language invented for the "Star Trek" show, attracts national attention.
Wichita Eagle, December 2, 1998A Sedgwick County Juvenile Court judge will decide today whether four children should be removed from a home police found littered with animal waste and whose parents spoke with them in a language created for "Star Trek" episodes. The children - ages 12, 9, 5 and 5 months - were taken into protective custody not because they spoke "Klingon" but because of the condition of their mobile home. Police Capt. Bob Circle said officers found animal droppings scattered through the home, which reeked of cat urine and feces. Nine cats and two ferrets were living there. Police also found an abundance of 'Star Trek' magazines, posters and memorabilia, and couldn't understand the father at first because he spoke to his wife and children in Klingon.
This was blogged long ago at Uffish Thoughts but it deserves reposting because Google doesn't seem to know about the original.