Clyde and Clementine Young did not have the slightest idea that it was their three sons who held 11 persons hostage at Washington's Islamic Mosque for two days this week until it was all over.

"We were shocked," said Mrs. Young, who said she had slept with her radio on to keep abreast of the hostage situatiuon. "I called their house and their wives told me. It was hard for us to believe." She added:

"My sons grew up in Sunday school. They have been in church since they were infants. We are peace-loving people. We don't pick up arms."

The Youngs spoke to a reporter on the front porch of the 65-year-old detached frame house they own on hilly High Street in Southeast Washington. On one side of the house is a garden apartment, on the other a vacant lot on which new townhouses are scheduled to be built.

Clyde Young, a 67-year-old retired government worker who earned extra money driving a taxi for 25 years, sat on the porch railing. His wife, Clementine, never emerged from behind the front screen porch.

They seemed alternately reluctant and eager to talk about the three sons - of a total of nine children - who had mysteriously, to them, embraced the Hanafi Muslim faith and then followed their spiritual leader, Hamaas Abdul Khaalis, in seeking vengeance for the death four years ago of seven persons at the upper 16th Street NW Hanafi house.

While a lot is now known about the Young brothers and how they developed in their Anacostic community - were neighbors described them as "polite and respectful" - very little is known about how and why their perspectives changed after they left home. Even their parents can only speculate.

Why they became Muslims remains a question for some. A further question, which baffles the Young family, is why the three brothers took part in the violent siege of last week.

The Youngs said they have spoken with their three sons since their release without money or surety bond Friday, but they declined to reveal what they said. Aside from Hamaas Khaalis, the Young brothers are the only defendants who were released pending trial out of a total of 12 Hanafi men arrested at the three locations where hostages were held.

The brothers and their families share a split-level house in Wheaton. All of them have been employed as taxi drivers by the Barwood Cab Co. in the District. Information provided by public records and by their parents provides a more detailed pitcure of three Washington sons.

The records show that Clyde C. Young, 37, known as Abdul Rahman, and Samuel L. Young, 22, known as Abdul Al-Qawee, each completed high school, while brother Philip Alvan Young, while brother Philip Alvan Young, 26, known as Abdul Rahim, attended Federal City College and obtained a degree in journalism from educationally progressive Goddard College in Plainfield, Vt.

Court records reveal lifelong community ties, and no criminal records.

Barwood Co. records show that Philip has been a D.C! street vendor and a freelance photographer. As a Federal City College stucent, he took a ecommunitcations class with WTOPTV anchorman Max Robinson. Robinson described him yesterday as a "questioning student" who achieved A or B grades in the class.

According to Barwood sources, Sam Young lost his company cab after year for failing to make a rental payment on it. A contributing factor, a company source said, was a passenger complaint that he kept a machete-type knife in the car.

In this practice, the source said, Sam Young was not unique. All three brothers kept such knives under the front seats of their cabs, the source said, describing Sam as the roughest mannered of the three.

The picture of machete-carrying men with alien-sounding names stands in sharp contrast to the expectations in older Youngs had for the three sons.

After rearing their children in AME church, Mr. and Mrs. Young said they were dismayed and chagrined to learn only a year ago that their sons were Muslims.

"When I found out they were Muslims, I warned them, because I don't like Muslim (faith)," said Mrs. Young. "They just looked at us and hung heads,"

They were pretty good boys growing up," said Young, who said he has been a taxi driver in Washington for 25 years. "I was superintendent of the Sunday school for 15 years. The boys worked with me. I brought them along.

We've always thought that in case is a registered nurse Another son, Charles, is a businessman in Washington according to Young. Philip had graduated from college with a degree in journalism Samuel had studied at Washington Technical Institute until his recent marriage.

We've always thought that in case we die we want our children to have has a good up-bringing" said Young, who noted that neither he nor his wife graduated from highschool.

"I think this Muslim stuff is something Philip picked up while he was at Goddard College. I didn't hear anything about it before then," Young continued.

Added Mrs. Young: "The funny thing about it, at the time the people got killed up on 16th Street (in 1973) none of my sons were up there with the Hanafis. They were out working. They had good jobs.

"Now, since they became Muslims, they all quit their jobs and they became cab drivers. We didn't send Philip to college to drive a cab. I don't know what's going on.

"The Muslim names sound strange. I first heard them on the radio. They're not the names I gave my sons. I've been praying through this whole thing but the one I feel really sorry for is Sam. He's not the Muslim type. I know he was there but he's not a Muslim.

"Sam was born in this house. Philip was born in this house," Mrs. Young continued. "My husband and I first met in church. We've always been church people. That's the reason I can'tunderstan how our children ever got mixed up in this. They were so active in church."

Said her husband: "When our boys became Muslim they tried to show us in the Koran that it was the only thing to believe. They even brought me a copy of the Koran. I didn't read it enough to suit them, so they took it back."

Even as the Youngs reeled from the news of their sons, there were other family problems that competed for their attention yesterday. They worried about the future of the infant child born last Dec. 17 to Philip and his wife. They busily prepared to attend the funeral of a cousin in York, Pa. who died Friday.