The Washington's inherited two interesting tendencies.
First, an obsession with owning land. Had Lawarance lived it is doubtful George would have ever owned Mount Vernon. But I think he would have owned land and had a large palacial home and even a plantation, possibly in the tidewater region of Virginia close to Williamsburg since Williamsburg was then the seat of power in Virginia.
Second, a tendency to die young, form what we know today it was probably from coronary heart disease. As George approached age 65 he commented on his own mortality and the fact that no man in his family had ever reached age 65. By the time George died at age 67 in 1799, I believe some or all of his younger brothers had already passed on.
Had Lawarance not died in 1752 at age 34, how long would he have lived? By 1776 he would have been 58 and reachingthe critical age for Washington men. However, perhaps in this timeline the men in the Washington family don't have this tendency to die early like that.
Had Lawarance and the other elder half brother Augustine both lived I'm sure they would have had considerable influence on George. As the eldest, Lawarance seems to have felt some responsibility toward his younger half siblings after their father's death.
What we cannot really know for sure is where Lawarance and Augustine would have stood in terms of The Revolution and how that might have influenced George. Might they have gotten George the commission he wanted, and what would that have done to history?
Would either or both of the elder Washington brothers have sided with The Brittish, or with the Rebels? How would that have influenced George? They might have had other influences on history. Had Lawarance and Augustine lived they would have I'm sure been involved in Virginia and Colonial politics. What broader influences might they have had there? There is so much that Lawarance or Lawarance and Augustine both living could have butterflyed. It could have even butterflyed away The Revolution entirely or caused it to be a much smaller revolution that failed. We have the possibility for lots of butterflys.
If Lawarance and Augustine both sided with the Rebels, what would it have done to The American Revolution to have three brothers from a very wealthy, powerful, and influential family all as major players in The Revolution? Again, lots of butterflys are possible.
Anyone want to take a chance at where those butterflys might have gone?