Why do People Recite their Lineages Ad Nauseum?

One thing that's always fascinated me about Americans is how proud they are to recite their ancestries. "I'm Scottish (note to all U.S. readers, if your ancestors hail from Scotland, you're Scottish, not 'Scotch' - which is a drink) and Irish", or "I have a small amount of Native American, English, and German" - etc., I'm sure you've heard people recite their racial or ethnic lineage ad nauseum as well. I wonder why people insist on recitating like they do, do they really think the other person - who 90% of the time tends to be someone who is not a close person to the recitating individual, usually just a co-worker or a neighbor - is actually paying attention? I fail to understand it.

I won't do that, but what I thought would be more entertaining would be to name some of the characters whom I've descended from, for fun!

On my dad's side (primarily Irish, Swedish, German), one of my ancestors long ago, named Duncan MacPherson, settled from Ireland in New York, sided with the British & fought against the Americans in the Revolutionary War!
On my mom's paternal side (Chilean), one of my ancestors was a pirate named either Kelly, or O'Kelly, whose ship sank in one of the harbors of Chile, settled in Chile, and married into the rest of our Chilean family
My great-grandfather on my mom's side (Catalonian) was named Joan (Catalunyan for Juan) Bardina i Castarà, the most famous person I descend from. Abuelito Juan was the first person ever to formally put into writing Catalonian grammar and its rules. An attorney and newspaper writer, he moved from Barcelona to Santiago, Chile in 1921 and had four kids, (gran-tio) Juan, Raquel, Marta, and my grandma, Maria Rebeca Huerta (de Bardina). Once settled in Santiago, he started his own succesful newspaper, La Semana Internacional, and published for 17 years . Abuelito Juan's newspaper was very succesful - he was awarded with El Gran Diploma de Honór by Chile for his work, while Bolivia bestowed him with El Gran Maestre de la Orden Nacional del Cóndor de los Andes.

((Gran)-Abuelito) Joan Bardina i Castarà, first row, second from right

Leading up to World War II Abuelito Juan, like most of Chile, wrote in support of Germany basing his allegiance on the overly punitive Treaty of Versailles the Allied Powers had imposed on it. In 1939, agents or liaisons from the United States sent by Franklin Roosevelt were sent to bribe the newspapers in Chile to switch their allegiances from Germany to the United States. Two well-known newspapers that continue to exist in Chile to this day took the bribes, but my great-grandfather did not, and had his newspaper shut down. As a result, Abuelito Juan had a massive stroke in 1948, and died in 1950 because of the stress the United States had put on him by threatening his livelihood for his political beliefs - which has made us, like many other Latin Americans, always skeptical of the United States's true motives whenever it involves itself in Latin America. They've named a street in Barcelona after him, and in 1984 a not-for-profit think-tank was established in Barcelona - also named after him!
While we supported Augusto Pinochet
on my mom's paternal side (Chilean, Huerta de Silva) my third-cousin was one of his political opponents in the Catholic Church, Cardinal Raúl Silva Henríquez.
The end!