The National Portrait Gallery turned an art exhibit opening into a family reunion last night. Eighty descendants of portrait painter Chester Harding traveled from all across the country to attend the preview of a show featuring works by their famous ancestor.

The relatives spanned four generations and nearly 80 years' age difference. Most had never met before. Jerry Wolff, 14, of Alexandria, and the youngest relative in attendance, was overwhelmed. "I didn't even know I had a relative that painted," he said. "I didn't know there was anyone famous in our family."

The Harding descendants gathered first at a private reception hosted by Chester Harding Lasell and Margaret Lasell Smith, great-great-grandchildren of the painter. They spent a lot of time trying to figure out familial relationships. "I get stuck every once in a while," acknowledged Smith, 84, of Rosemont, Pa.

The newly united clan then joined nearly 100 guests in the gallery's third-floor Victorian hall for a preopening dinner that also celebrated the new William Edward West exhibit. They continued introductions and reminiscences during a buffet supper of roast leg of lamb with sauce cassis, corn bread and nori chicken with dilled mayonnaise.

"What is sort of mind boggling about geneology is that you research one branch and then all of a sudden it dawns on you that it's just one tiny, tiny part. It's fascinating when you think how many people you have relationships with," said Caroline Jenny, 33, who came with her mother from Cazenovia, N.Y.

The group's strong sense of family pride was apparent in the way they talked about their ancestor, who lived from 1792 to 1866. "He Chester Harding must have been very charming," mused John Lord King Jenny of Wilmington, Del. "Apparently he was able to make people like him. He was not only able to get a very good likeness, but he was able to keep the people who sat for him amused."

No family is without its scandal, though, however small. According to great-granddaughter Katherine Deeble of Martha's Vineyard, Mass., her father went to St. Louis to visit Chester Harding Krum, the son of the St. Louis mayor, and met, fell in love with and married Chester Krum's daughter Flora, his first cousin once removed. "So I was my mother's second cousin. My father and grandfather were first cousins," explained Deeble. "My grandfather was a great tease and used to tell them they weren't legally married."

After dinner, Portrait Gallery director Alan Fern said of his new exhibits, "A Truthful Likeness: Chester Harding and His Portraits" and "William Edward West: Kentucky Painter":

"I don't know whether William Edward West had a large family, but I sure know Chester Harding did."