Question: What relation was Samuel P. Bush to the 41st President of the USA, George H. W. Bush?

Context paragraphs:
Presidency of George H. W. Bush: The presidency of George H. W. Bush began at noon EST on January 20, 1989, when George H. W. Bush was inaugurated as 41st President of the United States, and ended on January 20, 1993.  Bush, a Republican, took office after a landslide victory over Democrat nominee Michael Dukakis in the 1988 presidential election.  He was the first sitting vice president to be elected president since Martin Van Buren in 1836.  Later, Bush, the 41st president, and his oldest son, George W. Bush, the country's 43rd (2001–2009), would become only the second father and son pair to become president.  (John Adams and John Quincy Adams were the first.)  Bush was denied a second term in the 1992 presidential election, which was won by Democrat Bill Clinton.

Barbara Bush: Barbara Bush (née Pierce; born June 8, 1925) is the wife of George H. W. Bush, the 41st President of the United States, and served as First Lady of the United States from 1989 to 1993.  She is the mother of George W. Bush, the 43rd President, and Jeb Bush, the 43rd Governor of Florida.  She served as the Second Lady of the United States from 1981 to 1989.

USS George H.W. Bush: USS "George H.W. Bush" (CVN-77) is the tenth and final "Nimitz"-class supercarrier of the United States Navy.  She is named for the 41st President of the United States and former Director of Central Intelligence George H. W. Bush, who was a naval aviator during World War II.  "Bush"'s callsign is "Avenger", after the TBM Avenger aircraft flown by then-Lieutenant George Bush in World War II.  Construction began in 2003 at the Northrop Grumman Newport News shipyard's Dry Dock 12, the largest in the western hemisphere.  She was completed in 2009 at a cost of $6.2 billion and her home port is Naval Station Norfolk, Virginia.

George H. W. Bush: George Herbert Walker Bush (born June 12, 1924) is an American politician who was the 41st President of the United States from 1989 to 1993 and the 43rd Vice President of the United States from 1981 to 1989.  A member of the Republican Party, he was previously a congressman, ambassador, and Director of Central Intelligence.  He is the oldest living former President and Vice President.  Previously known as simply "George Bush", since 2001, Bush has often been referred to as "George H. W. Bush", "Bush 41", "Bush the Elder", or "George Bush Senior" to distinguish him from his eldest son, George W. Bush, the 43rd President of the United States.

Samuel P. Bush: Samuel Prescott Bush (October 4, 1863 – February 8, 1948) was an American businessman and industrialist.  He was the patriarch of the Bush political family.  He was the father of U.S. Senator Prescott Bush, grandfather of former U.S. President George H. W. Bush, and great-grandfather of former U.S. President George W. Bush and Governor Jeb Bush.

Inauguration of George H. W. Bush: The inauguration of George H. W. Bush as the 41st President of the United States was held on Friday, January 20, 1989.  The inauguration marked the commencement of the four-year term of George H. W. Bush as President and Dan Quayle as Vice President.  Chief Justice William Rehnquist administered the presidential oath of office to Bush and Associate Justice Sandra Day O'Connor administered the vice presidential oath of office to Quayle.

President George Bush Turnpike: The President George Bush Turnpike (PGBT) is a 52 mi toll road running through the northern, northeastern and western suburbs, forming a partial loop around Dallas, Texas, United States.  It is named for George H. W. Bush, the 41st President of the United States.  At its west end near Belt Line Road in Irving, State Highway 161 (SH 161) continues southwest to Interstate 20 (I-20) in Grand Prairie.  The discontinuous free frontage roads along the turnpike from I-35E in Carrollton east to its end at I-30 in Garland are assigned the State Highway 190 (SH 190) designation.  SH 190 signage appears only along the Garland, Richardson, Plano, and Carrollton sections of the frontage road with the undersign "frontage road only".  At intersections with city streets, only the Bush Turnpike signs are displayed, not the SH 190 signage.  Prior to the construction of the main lanes as a tollway, SH 190 was used as the name of the planned main lanes too.  Similarly, the part west of I-35E was planned as part of SH 161.  Bush Turnpike is signed as a north–south road from I-20 to I-35E (the "Western Extension"), an east–west road from I-35E to the Merritt Main Lane Gantry (the original sections) and as a north–south road from the Merritt Main Lane Gantry to I-30 (the "Eastern Extension"), as Bush Turnpike makes a nearly 90-degree curve in both places.

Union Pacific 4141: Union Pacific 4141 is an EMD SD70ACe locomotive owned by Union Pacific.  Its paint scheme is based on that of Air Force One and "George Bush 41" is painted on the sides in honor of the George Bush Presidential Library based on George H. W. Bush, the 41st President of the United States.

Presidency of George W. Bush: The presidency of George W. Bush began at noon EST on January 20, 2001, when George W. Bush was inaugurated as 43rd President of the United States, and ended on January 20, 2009.  Bush, a Republican, took office following a very close win over Democratic nominee Al Gore in the 2000 presidential election.  Bush, the 43rd president, is the eldest son of the 41st president, George H. W. Bush.  Bush was re-elected in 2004, defeating his Democratic opponent John Kerry.  He was succeeded by Democrat Barack Obama, who won the 2008 presidential election.

Dorothy Bush Koch: Dorothy Walker Bush Koch, often called "Doro", (born August 18, 1959) is an American author and philanthropist.  She is the daughter of the 41st President of the United States George H. W. Bush and former First Lady Barbara Bush, and the youngest and only still-living female sibling of George W. Bush, the 43rd President.

Supporting paragraphs: Samuel P. Bush George H. W. Bush
Answer: grandfather